PREPSA2010

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Question: 1

You are counseling the mother of a 3-month-old breastfed infant whose family has been urging her to introduce cereals to her baby’s diet. She asks your advice.

Of the following, the MOST likely outcome of introducing solid foods at this age is to

A. accelerate the development of oral-motor skills B. help the infant sleep through the night

C. increase the risk of food allergies

D. increase the risk of gastroesophageal reflux E. increase the risk of gastrointestinal infections

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Preferred Response: E Critique: 1

The most likely consequence of early (before 6 months of age) feeding of complementary foods such as cereals to breastfed infants is an increased likelihood of gastrointestinal infection. The direct relationship between early complementary feedings and the incidence of diarrheal illness is based on several case-control studies. In one investigation from Belarus, a large group of infants who were exclusively breastfed for more than 6 months was compared with a group receiving a mixed diet of human milk plus solids, with solids introduced between 3 and 6 months of age. Exclusively breastfed infants had a significantly reduced risk of one or more

gastrointestinal illnesses. Furthermore, other observations suggest that this effect may be enhanced with greater duration and exclusivity of breastfeeding. However, prior studies have failed to show any clear risk reduction in the prevalence of upper and lower respiratory tract illnesses, asthma, and otitis media among exclusively breastfed infants compared with infants who received a mixed diet of human milk and solids.

No available evidence supports the hypothesis that the introduction of solid foods either accelerates the development of oral-motor skills or helps infants to sleep through the night.

Data concerning the effect of early introduction of solids on the development of allergies are conflicting. The Belarus study found no reduction in risk for atopic eczema in exclusively

breastfed infants; a Finnish investigation showed a reduced eczema risk at 1 year but not at 5 years of age in a similar group. Although the Finnish study demonstrated a small reduction in any atopic condition for exclusively breastfed infants, the results were not statistically significant. Evidence also failed to demonstrate that early solid food introduction was associated with an increased incidence of positive skin prick tests.

Results of obesity studies also are inconclusive. In exclusively breastfed infants, solid food introduction prior to 6 months of age generally is associated with reduced human milk intake without accelerated weight gain. However, formula-fed infants may be encouraged to consume the same amount of formula, even after complementary feedings are introduced. This practice may lead to increased calorie consumption and excessive weight gain.

Gastroesophageal reflux (GER) is the result of transient relaxations of the lower esophageal sphincter. Studies using intraesophageal pH probe monitoring data have shown that the reflux index (RI) (percent time that esophageal pH is less than 4) is significantly greater in infants (RI mean upper limit of normal: ~12) than in older individuals (mean: ~6). The addition of solids to the diet does not influence the time to resolution of clinical GER during infancy, although the

frequency and severity of symptomatic reflux episodes may be reduced, at least in part, by thickening feedings or increasing solid consumption in appropriately aged infants.

The appropriate timing for introducing solid foods to the infant diet depends on development of both neuromuscular function and gastrointestinal maturation. The American Academy of Pediatrics supports exclusive breastfeeding for the first 6 postnatal months. However, from a developmental perspective, term infants often are capable of accepting solids (complementary foods) between 4 and 6 months of age. Maturational readiness to tolerate complementary feedings is indicated by loss of the extrusion reflex (usually by 4 months) and by the ability to swallow non-liquid foods. The most obvious risk posed by solid food consumption prior to reaching these developmental milestones is that failure to achieve oropharyngeal coordination for consuming solids may lead to aspiration.

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References:

Braganza SF, Adam HF. In brief: gastroesophageal reflux. Pediatr Rev. 2005;26:304-305. Available at: http://pedsinreview.aappublications.org/cgi/content/full/26/8/304

Fein SB, Labiner-Wolfe J, Scanlon KS, Grummer-Strawn LM. Selected complementary feeding practices and their association with maternal education. Pediatrics. 2008;122:S91-S97.

Available at:

http://pediatrics.aappublications.org/cgi/reprint/122/Supplement_2/S91?maxtoshow=&HITS=10&h its=10&RESULTFORMAT=&fulltext=Selected+complementary+feeding+practices+and+their+asso ciation+with+maternal+education&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetyp e=HWCIT

Kleinman RE. Complementary feeding. In: Pediatric Nutrition Handbook. 5th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2004:103-115

Kramer MS, Chalmers B, Hodnett ED, et al. Promotion of Breastfeeding Intervention Trial (PROBIT): a randomized trial in the Republic of Belarus. JAMA. 2001;285:413-420. Available at: http://jama.ama-assn.org/cgi/content/full/285/4/413

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Question: 2

You are called to labor and delivery to attend the vaginal delivery of a 37 weeks’ gestation male to a 24-year-old primiparous mother. She reports that her membranes ruptured 36 hours ago. She is afebrile.

Of the following, the maternal condition that is MOST likely to require antibiotic therapy for this neonate is

A. chorioamnionitis B. diabetes mellitus

C. group B streptococcal colonization D. preeclampsia

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Preferred Response: A Critique: 2

The mother described in the vignette has premature rupture of the membranes, which occurred 36 hours prior to her delivery. Premature rupture of the membranes is defined as rupturing of the amniotic sac not followed by the onset of labor within 8 hours. Preterm rupture of membranes is defined as rupturing of the amniotic sac before 37 completed weeks of gestation. Prolonged rupture of membranes (PROM) before delivery of the fetus increases the risk for early-onset neonatal sepsis (EONS); PROM of 18 hours or more is considered

significant.

Both term and preterm infants are at risk for EONS associated with PROM. However, the preterm infant delivered after PROM has a greater risk for infection than the term infant due to immature innate immune function (eg, immature phagocytic and neutrophil function) and potential lack of passively acquired transplacental immunity (prior to 32 weeks’ gestation). Two maternal conditions can increase the risk for EONS in the face of PROM: chorioamnionitis and maternal group B streptococcal (GBS) colonization. The former confers a risk for fetal infection that may not be treated adequately with maternal antibiotics. Hence, the newborn may continue to have partially treated bacteremia, pneumonia, or meningitis and require treatment for presumed sepsis. The latter is of import because infants born before 36 weeks’ completed gestation are more susceptible to GBS infection, especially in the face of PROM or chorioamnionitis. A sepsis evaluation and empiric treatment with a penicillin and an aminoglycoside is recommended for the preterm infant following PROM.

Maternal GBS colonization status is of most importance in deciding whether to evaluate and treat a preterm but not term infant unless the term infant has symptoms of infection. Maternal diabetes does not affect the treatment of an infant with antibiotics. Preeclampsia does not confer risk to the fetus or newborn for acquiring an infection in the face of PROM, but it may be associated with leukopenia, especially in the very low-birthweight newborn, and may have a negative impact on the newborn’s ability to clear infection. A first-trimester maternal urinary tract infection is of little import because it is remote from delivery. However, in a GBS-positive

pregnant woman who experiences a urinary tract infection that is due to GBS, the potential inoculum is greater in the neonate, which affects the evaluation and presumptive treatment of the newborn.

References:

American Academy of Pediatrics. Group B streptococcal infections. In: Pickering LK, Baker CJ, Kimberlin DW, Long SS, eds. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2009:628-634

Centers for Disease Control and Prevention. Guidelines for GBS: Recommendations. 2008. Available at: http://www.cdc.gov/groupbstrep/guidelines/recommendations.htm

Puopolo KM, Madoff LC, Eichenwald EC. Early-onset group B streptococcal disease in the era of maternal screening. Pediatrics. 2005;115:1240-1246. Available at:

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Schrag S, Gorwitz R, Fultz-Butts K, Schuchat A. Prevention of perinatal group B streptococcal disease. Revised guidelines from CDC. MMWR Recomm Rep. 2002;51(RR-11):1-22. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5111a1.htm

Thilo EH, Rosenberg AA. The newborn infant. In: Hay WW Jr, Levin MJ, Sondheimer JM, Deterding RR, eds. CURRENT Diagnosis & Treatment: Pediatrics. 19th ed. New York, NY: The McGraw-Hill Companies, Inc; 2009:Chapter 1. Available for subscription at:

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Question: 3

A mother brings her 9-year-old boy to your clinic because he has been complaining of being tired in physical education class at school for the past few months. When you ask him about his symptoms, he reports having trouble catching his breath after he runs. Past medical history is negative, and a review of systems reveals only a cough that occurs primarily at night several times a month. He has grown well, and findings on physical examination are normal.

Of the following, the MOST likely reason for his exercise intolerance is

A. cystic fibrosis

B. exercise-induced asthma C. iron deficiency anemia D. vocal cord dysfunction

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Preferred Response: B Critique: 3

Exercise intolerance is the failure to tolerate physical exercise at a level that would be expected for a person’s age and condition, such as described for the boy in the vignette. For the child, it is important to determine whether exercise intolerance is due to a primary pulmonary or extrapulmonary cause. Pulmonary causes include asthma, cystic fibrosis, and acute and chronic infections of the lung. Among the extrapulmonary causes of exercise intolerance are cardiac disorders such as congestive heart failure, neuromuscular disorders such as muscular dystrophy, anemia, and deconditioning.

Exercise intolerance is measured primarily by the maximal oxygen consumption test, and examining the components of maximal oxygen consumption can be useful in understanding the reasons for exercise intolerance associated with various disease states. The Fick equation for maximal oxygen consumption is:

VO2max = SVmax x HRmax x (CaO2 — CvO2)max

where VO2 = oxygen consumption, SV=stroke volume, HR=heart rate, CaO2=oxygen content of arterial blood, and CvO2=oxygen content of mixed venous blood. A sedentary lifestyle and certain cardiac diseases such as congestive heart failure and cyanotic heart disease can cause a decrease in stroke volume. Diseases such as asthma, cystic fibrosis, anemia, and vocal cord dysfunction lower the oxygen content of arterial blood. States causing muscle weakness, such as muscular dystrophy or general deconditioning, can result in decreased oxygen use by the tissues. Alterations in any of these components can lead to decreased maximal oxygen consumption and exercise intolerance.

The shortness of breath after running and a nighttime cough described for the boy in the vignette make exercise-induced bronchoconstriction (EIB), also called exercise-induced asthma, the most likely diagnosis. Children who have EIB generally experience shortness of breath, chest tightness, and cough approximately 10 to 15 minutes after beginning exercise.

Administration of a short-acting beta2 agonist or inhaled cromolyn sodium prior to exercising can help to prevent the symptoms. For patients who have poorly controlled asthma and experience EIB, the most appropriate management is the use of inhaled corticosteroids and possibly other maintenance medications to control overall asthma symptoms. If a child who has presumed EIB fails to respond to pretreatment with beta2 agonists or inhaled cromolyn sodium, other

diagnoses such as vocal cord dysfunction should be considered.

Vocal cord dysfunction is the paradoxic adduction of the vocal cords during inspiration, causing airway obstruction during exercise. Inspiratory wheezing and throat tightness are common symptoms, but cough at night is not. Cystic fibrosis is unlikely in any child who is growing well and has no extrapulmonary symptoms. Iron deficiency anemia can cause exercise-induced dyspnea, but the boy’s history is not suggestive of this condition. Wolff-Parkinson-White syndrome causes re-entrant tachycardia; syncope rather than exercise intolerance is the usual clinical manifestation.

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McColley SA. Extrapulmonary diseases with pulmonary manifestations. In: Kliegman RM,

Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:1846-1847

O’Byrne PM. Exercise-induced bronchoconstriction. UpToDate Online 16.3. 2008. Available for subscription at:

http://www.utdol.com/online/content/topic.do?topicKey=asthma/13974&selectedTitle=1~43&sour ce=search_result630

Owens S, Gutin B. Exercise intolerance. Pediatr Rev. 2000;21:6-9. Available at: http://pedsinreview.aappublications.org/cgi/content/full/21/1/6

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Question: 4

You are seeing a 1-year-old patient in your clinic for a health supervision visit. You explain the recommended screening tests for this visit to the medical student who accompanies you. Of the following, the MOST appropriate recommended screening test at this visit is

A. blood lead concentration by fingerstick B. blood lead concentration by venipuncture C. complete blood count with differential count D. serum ferritin

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The diagnosis of lead poisoning or increased lead absorption depends on the measurement of blood lead concentrations. In the 1990s, both the American Academy of Pediatrics and the Centers for Disease Control and Prevention recommended universal blood lead screening of 1-and 2-year-old children, but because of the substantial decrease in the prevalence of elevated blood lead concentrations, the criteria for screening are changing in many communities. Thus, it may be helpful to contact your local health department to determine if children in your area are at risk for environmental lead exposure.

Although blood lead concentration can be measured most accurately from a sample obtained by venipuncture, a capillary specimen obtained by fingerstick is the most appropriate screening test for the toddler described in the vignette. The specimen must be obtained carefully to avoid contamination from lead on the skin. Capillary specimen values greater than 10 mcg/dL (0.5 mcmol/L) must be confirmed by a venous sample because of the possibility of skin contamination causing a false-positive result.

Although obtaining a complete blood count with smear and measuring serum ferritin and serum iron may be useful in the diagnosis and management of children who have anemia, including that associated with environmental lead exposure, these tests are not definitive for determining exposure to environmental lead. Finally, hair evaluation for lead poisoning is neither sensitive nor specific due to the lack of correlation with blood lead values and should not be used.

References:

American Academy of Pediatrics Committee on Environmental Health. Lead exposure in children: prevention, detection, and management. Pediatrics. 2005;116:1036-1046. Available at:

http://pediatrics.aappublications.org/cgi/content/full/116/4/1036

Binns HJ, Campbell C, Brown MJ for the Advisory Committee on Childhood Lead Poisoning Prevention. Interpreting and managing blood lead levels of less than 10 mcg/dL in children and reducing childhood exposure to lead: recommendations of the Centers for Disease Control and Prevention Advisory Committee on Childhood Lead Poisoning Prevention. Pediatrics.

2007;120:e1285-e1298. Available at:

http://pediatrics.aappublications.org/cgi/content/full/120/5/e1285

Laraque D, Trasande L. Lead poisoning: successes and 21st century challenges. Pediatr Rev. 2005;26:435-443. Available at: http://pedsinreview.aappublications.org/cgi/content/full/26/12/435 Rischitelli G, Nygren P, Bougatsos C, Freeman M, Helfand M. Screening for elevated lead levels in childhood and pregnancy: an updated summary of evidence for the US Preventive Services Task Force. Pediatrics. 2006;118:e1867-e1895. Available at:

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prevention of domestic lead exposure in children. Cochrane Database Syst Rev. 2008;2:CD006047

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Question: 5

During the health supervision visit for a 14-year-old boy, you note that his body mass index (BMI) is at the 95th percentile. At last year’s health supervision visit, his BMI was at the 85th percentile.

Of the following, the complication for which this boy is at the HIGHEST risk is

A. atrial fibrillation B. hypothyroidism C. narcolepsy D. social isolation E. steatorrhea

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Preferred Response: D Critique: 5

Childhood obesity is one of the most common chronic conditions of childhood. It is believed to be strongly associated with a number of morbidities, including type 2 diabetes mellitus, hypertension, the metabolic syndrome, and psychosocial conditions. For individual children, the immediate psychosocial effects of social isolation, discrimination, and peer problems may accompany childhood obesity. Obese adolescents have been reported to have lower self-esteem as well as increased rates of sadness, social isolation, loneliness, and nervousness. Several studies have demonstrated the relationship between obesity, as measured by body mass index (BMI) and the psychosocial development of children.

Adolescent obesity is a strong predictor of adult obesity, and adult obesity has been associated with depression, especially in women. Studies also have suggested an association between depression in adolescence and higher BMI in adulthood. Whether depression leads to obesity or obesity causes depression is unclear. In contrast, there is a strong association between lower self-esteem and higher BMI across the elementary school years. In many

children, the presence of an increased BMI and obesity precedes low self-esteem, suggesting a causal relationship. Accordingly, prevention and management strategies for children who are overweight and obese should be undertaken early to minimize the impact on self-esteem and the other important psychosocial aspects of healthy development.

The boy described in the vignette, who meets the diagnostic criteria for obesity (BMI >95th percentile), may be at increased risk for obstructive apnea and resulting effects on the right ventricle, but he is not necessarily at a greater risk for atrial arrhythmias such as atrial fibrillation. Similarly, he may have poor sleeping habits, but obesity does not lead to narcolepsy. Although hypothyroidism can be associated with weight gain, no evidence suggests that obesity leads to hypothyroidism. Finally, obesity is not known to be a cause of steatorrhea.

References:

Goodman E, Whitaker RC. A prospective study of the role of depression in the development and persistence of adolescent obesity. Pediatrics. 2002;110:497-504. Available at:

Hesketh K, Wake M, Waters E. Body mass index and parent-reported self-esteem in elementary school children: evidence for a causal relationship. Int J Obes Relat Metab Disord.

2004;28:1233-1237. Available at: http://www.nature.com/ijo/journal/v28/n10/full/0802624a.html Ludwig DS. Childhood obesity–the shape of things to come. N Engl J Med. 2007;357:2325-2327. Available at: http://content.nejm.org/cgi/content/full/357/23/2325

Stunkard AJ, Wadden TA. Psychological aspects of severe obesity. Am J Clin Nutr. 1992;55(2 suppl):524S-532S. Available at: http://www.ajcn.org/cgi/reprint/55/2/524S

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Question: 6

A mother brings in her otherwise healthy 4-year-old son because of problems walking. He has not wanted to walk since this morning and only stands on tip-toe or crawls. He had an upper respiratory tract illness with a fever 1 week ago. On physical examination, the boy appears well, but he complains of leg pains bilaterally. He reports no back pain. His calf muscles are tender to palpation, but joints are not warm, red, or swollen. Patellar and ankle jerk reflexes are present bilaterally, and there is no clonus.

Of the following, the MOST appropriate initial diagnostic procedure is

A. antinuclear antibody measurement B. lumbar puncture

C. magnetic resonance imaging of the spine D. nerve conduction studies/electromyography E. serum creatine kinase measurement

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A child who has an acute or subacute gait disturbance represents a medical emergency. Diagnostic evaluation must be thorough, considering causes at all neuroanatomic levels: brain/cerebrum, cerebellum, brainstem, spinal cord, root, nerve, junction, and muscle. Prompt identification of hydrocephalus, spinal cord lesions, or Guillain-Barré syndrome can prevent lifelong neurologic damage or save a life.

The boy described in the vignette has symptoms only in his legs, with both weakness and leg muscle tenderness. Such findings typically localize to muscle and suggest the diagnosis of acute myositis. An elevated serum creatine kinase value (sometimes to more than 1,000 units/L) confirms the diagnosis. In children, acute myositis most often occurs after respiratory infections such as influenza. The condition is self-limited, rhabdomyolysis is unlikely, and no treatment is needed.

A spinal cord process that necessitates neuroimaging of the spine is very unlikely for this boy. Findings suggestive of such a diagnosis include flaccid reflexes (initially), loss of bowel and bladder function, and sensory deficits with a sensory level. A lumbar puncture is used to assess for acute inflammatory demyelinating polyneuropathy, also known as Guillain-Barré syndrome. The absence of back pain and the preservation of reflexes make this diagnosis unlikely. Nerve conduction studies/electromyography often are helpful when neuropathy is suspected in a child who has motor and sensory deficits plus loss of reflexes. The boy has no history or examination finding to support a rheumatologic disease that requires antinuclear antibody measurement.

References:

Compeyrot-Lacassagne S, Feldman BM. Inflammatory myopathies in children. Pediatr Clin North Am. 2005;52:493-520. Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/15820377 Mackay MT, Kornberg AJ, Shield LK, Dennett X. Benign acute childhood myositis: laboratory and clinical features. Neurology. 1999;53:2127-2131. Abstract available at:

http://www.ncbi.nlm.nih.gov/pubmed/10599793

Millichap JG. Benign acute myositis and influenza viral infection. AAP Grand Rounds. 2000;3:32. Available for subscription at: http://aapgrandrounds.aappublications.org/cgi/content/full/3/3/32

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Question: 7

You are called to the neonatal intensive care unit to evaluate a newly admitted 34-week

gestational age male infant who has respiratory distress. When you arrive, the baby is receiving oxygen supplementation by hood. You note that the baby’s weight, length, and head

circumference are all below the 10th percentile. He has excess hair over his forehead,

shoulders, and back (Item Q7). In addition, he is very irritable, despite correction of his oxygen saturation to 95%.

Of the following, this infant’s unusual findings are MOST likely related to prenatal exposure to

A. alcohol B. cocaine C. marijuana

D. methamphetamine E. tobacco

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The infant described in the vignette has features consistent with fetal alcohol spectrum disorders (FASDs). FASDs are characterized by a range of recognizable outcomes in infants exposed to alcohol prenatally, the most severe of which is fetal alcohol syndrome (FAS). FAS includes the presence of specific facial anomalies, such as short palpebral fissures, thin vermilion border of the upper lip, and smooth philtrum, as well as evidence of pre- or postnatal growth restriction (height or weight <10th percentile) and findings consistent with abnormal brain growth (head circumference <10th percentile) or brain development (structural brain anomalies). Maternal alcohol exposure need not be confirmed to make a diagnosis of FAS, but other syndromes and conditions that have overlapping features should be ruled out. Other categories of FASD include partial FAS with or without confirmed maternal alcohol exposure, alcohol-related birth defects, and alcohol-related neurodevelopmental disorder. Newborns affected by FAS frequently are irritable and tremulous, and although these symptoms suggest neonatal withdrawal, they can continue for months. Infants also can be unusually hirsute (ethnicity always must be considered when judging hirsutism), and this feature typically dissipates over the first 6 postnatal months (Item C7). Although there is no well-characterized neonatal alcohol withdrawal syndrome, the physician should be alert to signs of drug

withdrawal when FASD is suspected due to the frequent concomitant use of alcohol and drugs. Despite numerous publications describing deleterious effects of cocaine on the developing embryo and fetus, the impact of prenatal cocaine exposure remains uncertain. It is generally accepted that cocaine use in pregnancy increases the likelihood of placental abruption, and there is an increased incidence of sudden infant death syndrome in exposed infants. There also may be an increased risk for genitourinary and limb anomalies. There is no generally agreed-upon "cocaine syndrome." Because cocaine often is used in combination with other drugs, cigarettes, and alcohol, it can be difficult to discern what fetal abnormalities are cocaine-related.

Marijuana use in pregnancy is not known to be associated with an increased risk for birth defects, dysmorphic features, or developmental delay in exposed offspring.

Methamphetamines have not been shown to increase the risk for birth defects in exposed infants, although decreased birthweight has been reported in some exposed infants. A neonatal withdrawal syndrome that includes abnormal sleep patterns, tremulousness, poor feeding, and increased tone frequently is described. Concern has been raised for neurodevelopmental problems in later years, but further investigation is needed.

The effects of maternal smoking on pregnancy outcome continue to be an active area of study. Cigarette smoking is associated with an increased risk for miscarriage, reduced fetal weight, and abnormal placentation. There may be an increased risk for facial clefting, but cigarette smoking is not otherwise associated with major congenital anomalies.

References:

Cigarette smoking (tobacco). Teris. Available for subscription at: http://depts.Washington.edu/terisweb/teris

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Cocaine. Reprotox®. Available for subscription at: http://www.reprotox.org

Cocaine. Teris. Available for subscription at: http://depts.Washington.edu/terisweb/teris/

Hoyme HE, May PA, Kalberg WO, et al. A practical clinical approach to diagnosis of fetal alcohol spectrum disorders: clarification of the 1996 Institute of Medicine criteria. Pediatrics.

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Question: 8

A 15-year-old girl presents to the emergency department with right upper quadrant pain for 2 days that is severe enough to keep her out of school. Her appetite is decreased and she has nausea but no vomiting or diarrhea. She has mild discomfort with urination but no vaginal discharge. The only medication she is taking is combined oral contraceptive pills. Her last menstrual period was heavier that usual. Laboratory tests reveal:

•White blood cell count, 7.4x10 3/mcL (7.4x109/L) with 64% segmented neutrophils and 26% lymphocytes

•Total bilirubin, 0.4 mg/dL (6.9 mcmol/L) •Alanine aminotransferase, 14 units/L •Aspartate aminotransferase, 16 units/L

Her urine has 7 white blood cells per high-power field. Abdominal ultrasonography reveals a normal liver, spleen, gallbladder, and kidneys.

Of the following, the MOST likely diagnosis is

A. cholecystitis

B. Fitz-Hugh-Curtis syndrome C. hepatitis A infection

D. infectious mononucleosis E. pyelonephritis

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Preferred Response: B Critique: 8

Both the American Medical Association’s Guidelines for Adolescent Preventive Services and Bright Futures recommend that all adolescents should be asked annually about involvement in sexual behaviors that may result in unintended pregnancy and sexually transmitted infections (STIs), including human immunodeficiency virus infection. In addition to annual screening, the possibility of a pregnancy or an STI should be considered at every visit with an adolescent, and the last menstrual period should be documented.

The laboratory results for this girl rule out hepatitis, including that caused by mononucleosis, and biliary tract obstruction. Fitz-Hugh-Curtis syndrome or perihepatitis presents as right upper quadrant pain that results from inflammation of the liver capsule from ascending pelvic infection. Although typically associated with salpingitis, it can exist without other signs of pelvic

inflammatory disease and may mimic other abdominal emergencies. The absence of fever and the location of pain for this girl make pyelonephritis unlikely. Pyuria raises the possibility of urethritis, which commonly occurs with Neisseria gonorrhoeae and Chlamydia trachomatis infections. C trachomatis can cause inflammation of the genital tract without the classic

symptoms and signs of pelvic inflammatory disease. Often, heavier menstrual flow may be the only symptom.

References:

Burstein GR, Murray PJ. Diagnosis and management of sexually transmitted disease pathogens among adolescents. Pediatr Rev. 2003;24:75-82. Available at:

http://pedsinreview.aappublications.org/cgi/content/full/24/3/75

Elster AB, Kuznets NJ, eds. American Medical Association Guidelines for Adolescent

Preventive Services (GAPS): Recommendations Monograph. Chicago, Ill: American Medical Association; 1997. Available at: http://www.ama-assn.org/ama/upload/mm/39/gapsmono.pdf Hagan JF Jr, Shaw JS, Duncan P. Bright Futures: Guidelines for Health Supervision of Infants, Children and Adolescents. 3rd ed. Elk Grove, Ill: American Academy of Pediatrics; 2008 Hammerschlag MR. Chlamydia trachomatis and Chlamydia pneumoniae infections in children and adolescents. Pediatr Rev. 2004;25:43-51. Available at:

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Question: 9

You are evaluating a 4-year-old boy in the emergency department for septic shock. On physical examination, his heart rate is 140 beats/minute, respiratory rate is 30 breaths/minute, and blood pressure is 65/40 mm Hg.

Of the following, the MOST appropriate next step is administration of

A. 5 mL/kg of 25% albumin B. 5 mL/kg of 3% normal saline C. 10 mL/kg of 5% albumin

D. 20 mL/kg of 0.45% normal saline E. 20 mL/kg of 0.9% normal saline

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The boy described in the vignette is exhibiting signs and symptoms of septic shock, which is defined as the presence of sepsis and cardiovascular organ dysfunction. Septic shock is a medical emergency that requires prompt recognition and treatment.

One of the most important factors in lowering the mortality associated with septic shock is early and aggressive fluid resuscitation, defined as isotonic fluid boluses of 20 mL/kg titrated according to clinical assessment of adequacy of cardiac output, such as heart rate, urine output, and level of consciousness. Often, 60 mL/kg is needed for the initial resuscitation of a child who has septic shock.

The choice of fluid (crystalloid versus colloid) for use in shock resuscitation has been the subject of much debate, with little evidence to support the superiority of one over the other. In this scenario, 20 mL/kg of normal saline is preferred over 10 mL/kg of 5% albumin solely due to the larger volume administered. Initial fluid boluses should be 20 mL/kg, and often 60 mL/kg or more is required in the first hour of shock resuscitation.

The decision to use 5% albumin or normal saline often is dependent on institutional preferences. Both fluids are isotonic and increase intravascular volume, although a greater volume of saline is needed acutely to achieve the same effect. When endothelial integrity is

altered, albumin can leak into the interstitium and increase edema formation. In addition, albumin is considerably more expensive than normal saline, can produce hypocalcemia, and has a small risk of allergic reaction. In a large double-blind study comparing the use of 4% albumin with normal saline for fluid resuscitation of nearly 7,000 adult patients in the intensive care unit, investigators were unable to demonstrate statistical differences in mortality, length of intensive care unit and hospital stay, days of mechanical ventilation, or need for renal replacement therapy. A post-hoc analysis demonstrated an association with increased mortality in those patients who had traumatic brain injury and were treated with 4% albumin.

Although research is ongoing on the use of smaller amounts of hypertonic solutions for hemorrhagic shock, there is little research to date on its use in septic shock. Therefore, neither the administration of 3% normal saline nor 25% albumin is indicated. A 0.45% normal saline solution is a hypotonic fluid that would not be used for initial resuscitation.

References:

Brierly J, Carcillo JA, Choong J, et al. Clinical practice parameters for hemodynamic support of pediatric and neonatal septic shock: 2007 update from the American College of Critical Care Medicine. Crit Care Med. 2009;37:666-688

Dellinger RP, Levy MM, Carlet JM, et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008. Crit Care Med. 2008;36:296-327.

Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/18158437

Finfer S, Bellomo R, Boyce N. French J, Myburgh J, Norton R; SAFE Study Investigators. A comparison of albumin and saline for fluid resuscitation in the intensive care unit. N Engl J Med. 2004;350:2247—2256. Available at: http://content.nejm.org/cgi/content/full/350/22/2247

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Gupta M. Saline or albumin in the ICU. AAP Grand Rounds. 2004;12:16-17

McKiernan MA, Lieberman SA. Circulatory shock in children: an overview. Pediatr Rev.

2005;26:451-460. Available at: http://pedsinreview.aappublications.org/cgi/content/full/26/12/451 SAFE Study Investigators; et al. Saline or albumin for fluid resuscitation in patients with traumatic brain injury. N Engl J Med. 2007;357:874-884. Available at:

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Question: 10

You are examining a 6-year-old girl at her annual health supervision visit. She has Sexual

Maturity Rating 3 pubic hair, but no axillary hair. Her mother notes that the child has had an adult body odor for about 6 months. You cannot detect breast tissue, and she does not have

clitoromegaly. You examine her growth chart for height (Item Q10). Of the following, the MOST important test to perform at this time is

A. bone age radiography

B. magnetic resonance imaging of the head C. pelvic ultrasonography

D. serum estradiol measurement E. serum testosterone measurement

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Bone age radiographs can offer useful information about the adult height potential of healthy children who have bone ages of more than 7 years. In addition, a bone age that is advanced, in contrast to chronologic age, can offer some understanding of the length of time or the severity of exposure to sex steroids, particularly estrogen, which is responsible for epiphyseal

advancement. Similarly, a bone age that is delayed in relation to chronologic age can offer some inference as to the length of time of endocrine deficiency disorders such as hypothyroidism or chronic nutritional disorders such as celiac disease. However, bone age radiographs do not permit accurate height predictions in children who have bone ages less than 7 years and cannot offer appropriate height predictions for children who have abnormal growth patterns because of bone disorders or other growth disorders. Studies have shown that in children who have

isolated premature pubic or axillary hair development (premature pubarche or adrenarche), a bone age radiograph that is more than 1 year advanced compared with chronologic age increases the possibility of a serious underlying disorder such as late-onset congenital adrenal hyperplasia.

The girl described in the vignette has premature adrenarche or pubarche, the early appearance of the physical signs of adrenal puberty. Her growth chart reveals a small

acceleration in height, which is consistent with this diagnosis (Item C10). She has no evidence of either ovarian puberty (thelarche or breast tissue) or exposure to potent androgens

(clitoromegaly). An increase in adrenal production of weak androgen precursors

(dehydroepiandrosterone [DHEA] and dehydroepiandrosterone sulfate [DHEA-s]) can be identified in most children between 4 and 6 years of age. However, the earliest signs of adrenal puberty (adult body odor, pubic hair) usually occur at the same time or a few months after

thelarche. Rare children may have higher DHEA and DHEA-s values before the age of 7 years or may be particularly sensitive to low circulating concentrations of these hormones. Such children, including the girl in the vignette, come to medical attention because of early adult body odor and pubic and/or axillary hair.

The most likely worrisome possibility in the differential diagnosis for children who have premature adrenarche is late-onset congenital adrenal hyperplasia. A bone age radiograph reading within 1 year of the child’s actual age effectively rules out the diagnosis. Magnetic resonance imaging of the head might be indicated in a female child who has early true sexual precocity (activation of the hypothalamic gonadotropic axis with thelarche), but there is no indication for such a study in this child. Pelvic ultrasonography is indicated if there is suspicion about an androgen-producing ovarian tumor, but the slow progression and lack of clitoromegaly makes this very unlikely for this girl. Measures of serum estradiol and testosterone are not useful in this situation. The child’s lack of thelarche or clitoromegaly indicates low estradiol and testosterone concentrations, respectively, and standard commercial assays do not provide accurate results at the low concentrations of estrogen and testosterone found in early puberty. Her growth at a higher percentile is typical of girls who will be slightly early maturers and are having the mid-childhood growth spurt, sometimes attributed to adrenarche.

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Ibánez L, Jiménez R, de Zegher F. Early puberty-menarche after precocious pubarche: relation to prenatal growth. Pediatrics. 2006;117:117-121. Available at:

Kaplowitz P. Clinical characteristics of 104 children referred for evaluation of precocious puberty. J Clin Endocrinol Metab. 2004;89:3644-3650. Available at:

http://jcem.endojournals.org/cgi/content/full/89/8/3644

Kaplowitz PB. Precocious puberty. eMedicine Specialties, Pediatrics: General Medicine, Endocrinology. 2007. Available at: http://emedicine.com/ped/TOPIC1882.HTM

Muir A. Precocious puberty. Pediatr Rev. 2006;27:373-381. Available at: http://pedsinreview.aappublications.org/cgi/content/full/27/10/373

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Question: 11

You are examining a 4-year, 11-month-old child during her health supervision visit. Her mother has been home with her full time since birth. The friendly, happy child tells you about her trip to the zoo last week. She asks if you like animals and counts out loud 10 different animals she saw. When given a crayon, she is able to write her name stating the letters as she writes them. Her mother expresses concern about her beginning kindergarten next month because she just meets the age cut-off for kindergarten entry. She inquires about the factors that will help determine if her child is ready to attend school.

Of the following, the MOST appropriate response is that the girl should

A. be able to maintain attention during story time for at least 20 to 25 minutes B. be able to state her birthday and address

C. be able to tolerate separations from her parent for several hours at a time D. identify upper and lower case letters

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Preferred Response: C Critique: 11

Children are socially ready to attend school when they are able to separate from their parents for several hours at a time. They are expected to pay attention to the teacher, follow the classroom routine, play well with others, and take turns. During classroom group-based

activities, the young child should be able to pay attention to the teacher for 10 to 15 minutes, sit quietly, and listen to the teacher without bothering peers or disrupting the activity. Children also should be able to relate personal experiences and tell stories.

Children entering kindergarten should know color names, be able to count to 10, retell a story, identify some printed letters, and print their names. Knowing their addresses and birth dates and being able to identify both upper and lower case letters is expected of children entering first grade. Because the child described in the vignette has the prerequisite skills for kindergarten, a psychoeducational evaluation is not indicated at this time.

References:

High PC and the Committee on Early Childhood, Adoption, and Dependent Care and Council on School Health. School readiness. Pediatrics. 2008;121:e1008-e1015. Available at:

Kaplan-Sanoff M. School readiness. In: Parker S, Zukerman B, Augustyn M, eds. Developmental and Behavioral Pediatrics: A Handbook for Primary Care. 2nd ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2005:285-288

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Question: 12

A family comes to your office for consultation regarding a 3-week trip to India they are planning to take in 3 months. The children, a 9-year-old boy and a 7-month-old girl, are well, and their immunizations are up to date.

Of the following, the MOST appropriate prophylaxis to provide in preparation for travel is

A. chloroquine for both children

B. hepatitis A vaccination for both children C. measles vaccination for the girl

D. polio vaccination for the boy E. typhoid vaccine for both children

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Protection against infectious diseases is an important issue in preparing children and adults for international travel. Clinicians can obtain specific knowledge of available vaccines and prophylaxis for certain conditions from the American Academy of Pediatrics 2009 Report of the Committee on Infectious Diseases (Red Book®) and the travelers’ health site of the Centers for Disease Control and Prevention. Travel to India involves a potentially increased exposure to malaria, hepatitis A, measles, polio, and Salmonella typhi. However, there are other

considerations in recommending various preventive measures for travelers.

Measles may be encountered more commonly in many parts of the world, including India. Accordingly, measles vaccine is recommended for 6- to 11-month-old children, and the 7-month-old girl in the vignette should be given a dose of measles vaccine. She still will require two doses of measles-containing vaccine after 1 year of age because the immune response may be suboptimal at her young age. If the 9-year-old boy is up to date on immunizations, he requires no additional measles vaccination.

Although exposure to malaria is a concern on a prolonged trip to India, resistance to chloroquine is a major concern in this region, as it is in all of South and Southeast Asia, sub-Saharan Africa, and tropical areas of South America. Available agents for resistant malaria prophylaxis in infants and children include atovaquone/proguanil and mefloquine. Doxycycline can be used in children older than 8 years of age.

Hepatitis A is a concern, but hepatitis A vaccine is not approved in children younger than 1 year of age. Intramuscular immunoglobulin is recommended for children younger than 1 year of age, as the baby in the vignette, traveling to an endemic area. The boy should receive his first dose of hepatitis A vaccine at least 2 to 4 weeks before departure if he has not been immunized previously, with completion of the two-dose series 6 to 12 months later.

Although polio exposure may be a concern, if both children are up to date in their vaccination series, no additional polio vaccine is indicated. Finally, typhoid vaccine might be indicated for a trip to India that lasts longer than 2 weeks, but neither of the two licensed vaccines is indicated in children younger than 2 years of age.

References:

American Academy of Pediatrics. International travel. In: Pickering LK, Baker CJ, Kimberlin DW, Long SS, eds. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2009:98-104

Centers for Disease control and Prevention. Travelers’ Health Web site. Available at: http://wwwn.cdc.gov/travel/default.aspx

Centers for Disease Control and Prevention (CDC). Update: measles—United States, January–July 2008. MMWR Morbid Mortal Wkly Rep. 2008;57:893-896. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5733a1.htm

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Question: 13

You are evaluating a 2-year-old girl who was adopted from an orphanage in Eastern Europe. She has had a pruritic rash since she was brought to the United States 3 weeks ago. According to the mother, the rash is so pruritic that the girl must wear socks on her hands at night to prevent her from scratching. Physical examination demonstrates multiple 2- to 3-mm

erythematous papules and vesicles around her waist, in her inguinal folds, on her neck, and on the palms and soles (Item Q13). No other focal findings are evident on physical examination. Of the following, the MOST appropriate agent with which to treat this patient is

A. acyclovir orally

B. hydrocortisone topically C. hydroxyzine orally D. permethrin topically E. prednisone orally

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Scabies is a common disorder caused by infestation with the mite Sarcoptes scabiei. Scabies is contracted by prolonged close personal contact with an infected person, usually in situations such as families with school-age children or individuals living in close quarters, such as the orphanage described for the girl in the vignette.

Permethrin, an insecticide that has been available since 1989, is a safe and effective treatment for scabies. Permethrin acts by disrupting the sodium channel current, resulting in delayed repolarization, paralysis, and death of the parasite. It is effective during all stages of the life cycle of the parasite. Because of its excellent safety profile, 5% permethrin cream is the first-line drug for the treatment of scabies, especially among patients who have neurologic disorders and infants and young children. Lindane, an agent that was used in the past, no longer is recommended. The 1% solution of permethrin used to treat head lice has too low of a concentration to treat scabies effectively.

Permethrin has a low potential for toxicity but occasionally may cause redness of the skin, burning, and stinging with application and has been associated with rash and diarrhea. It is not recommended for use in infants younger than 2 months of age or for pregnant women.

Acyclovir is an antiviral agent used to treat herpesvirus infections and is not effective in the treatment of scabies. Topical hydrocortisone and oral hydroxyzine can be used to alleviate the itching, and oral prednisone may decrease the inflammation of scabies, but none of these agents is used to treat the infection.

References:

American Academy of Pediatrics. Scabies. In: Pickering LK, Baker CJ, Kimberlin DW, Long SS, eds. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2009:589-591

Downs A. Comparing antiscabies treatments. Arch Dermatol. 1997;133:526

Schultz MW, Gomez M, Hansen RC, et al. Comparative study of 5% permethrin cream and 1% lindane lotion for the treatment of scabies. Arch Dermatol. 1990;126:167-170. Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/1689135

Strong M, Johnstone P. Interventions for treating scabies. Cochrane Database Syst Rev. 2007;3:CD000320. Available at:

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Question: 14

An 18-month-old girl who has a 2-day history of vomiting with reduced oral intake presents to the clinic with a 24-hour history of nonbloody diarrhea. She was previously well. Upon further questioning, her mother reports a reduced number of wet diapers prior to the onset of diarrhea. She states that the girl is having four to five loose stools per day. You estimate the girl to be 5% dehydrated.

Of the following, the MOST likely additional examination finding is

A. bounding peripheral pulses B. capillary refill of 4 seconds C. hypotension

D. periorbital edema E. tachycardia

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Causes of dehydration in the pediatric patient include fluid losses from the gastrointestinal tract (vomiting or diarrhea) and less commonly, fluid losses due to excessive urinary production, as can occur in children who have urinary concentrating defects (due to renal dysplasia or diuretics).

Total body water constitutes approximately 60% of the body weight in children. Two thirds of the body fluid is contained within the intracellular compartment and one third within the extracellular compartment. The extracellular fluid compartment is divided further into the interstitial compartment (75%) and the intravascular compartment (25%).

Dehydration affects both the intracellular and extracellular compartments, but most physical signs and symptoms result from a reduction of intravascular volume (IVV). Clinically, the IVV can be expressed as the effective circulating blood volume (ECBV), which represents the volume and pressure providing perfusion to the tissues. A patient who has a low IVV has a low ECBV, but a patient who has a high IVV or normal IVV also may have a low ECBV if cardiac

dysfunction also is present.

Children who have gastroenteritis and mild-to-moderate dehydration, such as the child described in the vignette, can maintain cardiac output and blood pressure by increasing heart rate and effective myocardial contractility. Therefore, tachycardia is the most common clinical finding in this setting. Hypotension is sign of severe dehydration. Other signs in more advanced dehydration (approaching 10%) are decreased skin turgor, bounding pulses, and decreased capillary refill. Periorbital edema is not expected in the clinical setting of mild dehydration. References:

Armon K, Stephenson T, MacFaul R, Eccleston P, Werneke U. An evidence and consensus based guideline for acute diarrhoea management. Arch Dis Child. 2001;85:132-142. Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/11466188

Boineau FG, Lewy JE. Estimation of parenteral fluid requirements. Pediatr Clin North Am. 1990;37:257-264. Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/2184395 Gorelick MH, Shaw KN, Murphy KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics. 1997;99;e6. Available at:

Hill LL. Body composition, normal electrolyte concentrations, and the maintenance of normal volume, tonicity, and acid-base metabolism. Pediatr Clin North Am. 1990;37:241-256. Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/2184394

Rose BD, Post TW. Regulation of the effective circulating volume. In: Clinical Physiology of Acid-base and Electrolyte Disorders. 5th ed. New York, NY: McGraw-Hill Medical Publishing Division; 2001:258-284

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Question: 15

A 10-year-old boy presents to the clinic complaining of tongue and mouth itching within a few minutes after eating apples. His mother states that he has not experienced these symptoms with other foods, but they occur every time he eats a fresh apple. He denies systemic symptoms, and the oral symptoms resolve within a few minutes. Other than allergic rhinitis in the spring months, he is healthy.

Of the following, you are MOST likely to advise his mother that

A. allergy skin testing to fresh apples probably will have negative results B. cooking the apple will not alter its allergenicity

C. her son should avoid eating all fruits D. her son should avoid milk products

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The boy described in the vignette is exhibiting a common form of food allergy called food pollen syndrome or oral allergy syndrome (OAS). OAS is seen in 30% to 40% of children who have allergic rhinitis. Certain foods contain proteins that are similar to airborne allergens, and patients who are allergic to an aeroallergen are at risk of developing reactions to the cross-reacting food protein (Item C15).

In most cases, symptoms are isolated to the oropharynx, where food comes in contact with a mucosal surface, and include lip, tongue, and oral mucosal pruritus; tingling; and occasionally angioedema. Interestingly, because these food proteins are heat-labile, cooking the food (eg, apple pie) negates its antigenic properties. Although symptoms typically are mild, there are reports of severe reactions. In one recent review involving 1,361 patients who had OAS, 8.7% experienced systemic symptoms outside the gastrointestinal tract, 3% experienced symptoms other than oral symptoms, and 1.7% experienced anaphylactic shock.

Because OAS is relatively specific to particular cross-reacting food(s), patients do not need to avoid other fruits or vegetables to which they have not experienced reactions. Avoidance of unrelated foods (eg, milk, eggs) is not recommended unless the history suggests a previous reaction. The decision to avoid causative foods can be based on the severity of reaction. Referral to an allergist typically is reserved for situations when skin testing is desired or if the child has experienced systemic symptoms. Skin testing is performed using a commercial extract or the fresh fruit or vegetable. When using fresh food, the sensitivity of skin testing with a

history of reproducible reactions is close to 90%, while the negative predictive value is more than 90%. The skin prick device is pressed into the food and then pressed in the skin (so-called "prick-prick" skin test).

Other immunoglobulin (Ig) E food reactions include atopic dermatitis, eosinophilic esophagitis, and specific food allergy. In the United States, 85% of specific food allergies are due to egg, milk, wheat, soy, peanuts, tree nuts, fish, and shellfish. Most children who have IgE food allergies react to only one or two causative foods, although children who have tree nut allergy, atopic dermatitis, and eosinophilic esophagitis often have IgE-mediated reactions to multiple foods.

References:

Hyams JS. Food allergy (food hypersensitivity). In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:1585-1586

Ma S, Sicherer S, Nowak-Wegrzyn A. A survey on the management of pollen-food syndrome in allergy practices. J Allergy Clin Immunol. 2003;112:784-788. Abstract available at:

Sampson HA, Leung DYM. Adverse reactions to foods. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:986-989

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Sicherer SH, Sampson HA. 9. Food allergy. J Allergy Clin Immunol. 2006;117(2 suppl mini-primer):S470-S475. Abstract available at: http://www.ncbi.nlm.nih.gov/pubmed/16455349

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Question: 16

A 5-year-old boy who has epilepsy and severe developmental delay is brought to the

emergency department because of increasing somnolence over the past 12 hours. His mother reports that his activity level has decreased over the past 2 days, and this morning he was difficult to arouse. He has not been otherwise ill and has not had any seizures for the past 6 months. His antiepileptic medications include phenobarbital and oxcarbazepine. The doses recently were increased. On physical examination, the boy is difficult to arouse and moans to painful stimulation. His heart rate is 70 beats/min, respiratory rate is 18 breaths/min, and blood pressure is 80/50 mm Hg.

Of the following, the MOST likely additional abnormality on physical examination of this child is

A. dilated pupils

B. hyperactive bowel sounds C. hyperreflexia

D. hypothermia E. tremors

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The patient described in the vignette is exhibiting signs and symptoms consistent with a sedative-hypnotic overdose, including coma, bradycardia, bradypnea, and hypotension. Although most antiepileptic drugs can cause lethargy at high doses, barbiturates (eg, phenobarbital) are particularly sedating. The central nervous system depressant effects of barbiturates are primarily caused by drug action on the inhibitory neurotransmitter gamma aminobutyric acid (GABA). Barbiturates both increase GABA activity and directly stimulate GABA receptors. They also competitively inhibit glutamate, an excitatory neurotransmitter, from binding to receptors.

Other physical findings that may be present in the setting of a sedative/hypnotic overdose include hypothermia, hyporeflexia, hypoactive bowel sounds, and decreased muscular activity. Pupillary light reflex is slowed, but pupillary size usually is normal.

References:

Lafferty KA. Toxicity, barbiturate. eMedicine Specialties, Emergency Medicine, Toxicology. 2008. Available at: http://www.emedicine.com/emerg/topic52.htm

Schachter SC. Pharmacology of antiepileptic drugs. UpToDate Online 16.3. 2008. Available at: http://www.utdol.com/online/content/topic.do?topicKey=epil_eeg/5220&selectedTitle=1~150&sou rce=search_result630

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Question: 17

During a routine health supervision visit, the mother of a 2½ month-old male infant tells you that the baby has been experiencing bloating and flatulence. His diet consists of 5 to 6 oz of a cow milk-based formula given five times per 24 hours. Because of frequent spitting-up, his mother recently added rice cereal to each bottle. He has two to three seedy stools per day. On physical examination, the baby is alert and vigorous. His length and weight are tracking between the 50th and 75th percentiles. The infant’s mother asks you whether switching to a soy protein-based formula will help her baby’s "gassiness."

Of the following, the MOST likely the cause of this infant’s symptoms is

A. cow milk protein allergy B. excessive energy intake C. incomplete starch digestion D. lactose malabsorption

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The infant described in the vignette has been given formula thickened with rice cereal to ameliorate spitting-up. Following the introduction of cereal, his mother has noted increased "gassiness." The most likely cause of this symptom is incomplete starch digestion.

Development of the digestive-absorptive function of the gastrointestinal tract is not complete at birth. The newborn can assimilate considerable amounts of complex carbohydrates through hydrolysis by salivary gland amylase until pancreatic function and small intestinal intraluminal pancreatic amylase activity mature. Nevertheless, until pancreatic maturity is achieved, and certainly in infants younger than 4 months of age, dietary starches may be hydrolyzed

incompletely. As a result, increased amounts of undigested carbohydrate pass into the colon, where bacterial fermentation results in gas production that may cause the symptoms described for the infant in the vignette.

A diagnosis of cow milk protein allergy frequently is considered in the differential diagnosis of a variety of diverse gastrointestinal complaints. Symptoms that may be associated with cow milk protein intolerance include diarrhea, failure to thrive, hypoproteinemia, hematochezia, anemia, and vomiting as well as other cutaneous and systemic manifestations of atopy. The relationship between infantile colic and cow milk protein allergy remains highly controversial, particularly when fussiness or irritability is the sole complaint. For a thriving infant who develops vague gastrointestinal symptoms after the type of dietary changes described in the vignette, cow milk protein allergy should be considered only after ruling out other, more likely causes, such as incomplete digestion of complex carbohydrates.

It is unlikely that the infant described in the vignette has excessive energy intake because his weight gain is not excessive, and thickening of the formula does not appreciably add to energy intake in an infant who is consuming 25 to 30 oz of formula per day.

Lactase concentrations reach mature values in the small intestine by the 36th week of gestation in all healthy infants. Congenital or early-onset primary lactose intolerance is an extremely rare condition that is associated with severe diarrhea and inanition. It typically

presents with voluminous diarrhea soon after the first feedings of human milk or cow milk-based formula. During infancy and childhood, secondary lactase deficiency may occur as a

consequence of intestinal mucosal damage following a prolonged diarrheal illness, as a result of other intestinal disorders (eg, celiac disease), or in association with malnutrition.

Sucrase-isomaltase (SI) deficiency is the most common congenital disaccharidase deficiency. Diarrhea is a virtually universal symptom of SI deficiency and may be associated with poor weight gain. Symptoms usually appear in older infants following the introduction of sucrose-containing foods, particularly fruits and juices. Infants who have SI deficiency also do not tolerate soy or protein hydrolysate formulas because both sucrose and glucose polymers are maldigested and malabsorbed.

References:

Craig WR, Hanlon-Dearman A, Sinclair C, Taback S, Moffatt M. Metoclopramide, thickened feedings, and positioning for gastro-oesophageal reflux in children under two years. Cochrane Database Syst Rev. 2004;3:CD003502. Available at:

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http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD003502/frame.html Hall RT, Carroll RE. Infant feeding. Pediatr Rev. 2000; 21:191-200. Available at:

http://pedsinreview.aappublications.org/cgi/content/full/21/6/191

Montes RG. Carbohydrate malabsorption. In: Rudolph CD, Rudolph AM, Hostetter MK, Lister G, Siegel NJ, eds. Rudolph’s Pediatrics. 21st ed. New York, NY: McGraw-Hill; 2003:1423-1427 Thomas DW, McGilligan K, Eisenberg LD, Lieberman HM, Rissman EM. Infantile colic and type of milk feeding. Am J Dis Child. 1987;141:451-453. Abstract available at:

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Question: 18

You are asked by your pediatric resident on rounds why you remove umbilical artery catheters in very low-birthweight infants in your nursery by postnatal day 7.

Of the following, the BEST reason for such removal is to prevent

A. anemia

B. hyperglycemia C. hypotension D. sepsis

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Umbilical access to the arterial and venous circulation is a mainstay of early monitoring for the critically ill newborn. The umbilical artery provides access to the central arterial circulation via the inferior iliac artery, common iliac artery, and aorta. An umbilical arterial catheter (UAC) is indicated for only two uses: the frequent sampling of arterial blood for blood gas analysis in a newborn who has respiratory distress or the provision of inline transduced arterial blood pressure monitoring. In either circumstance, the risks of placing and using a UAC must be considered.

Among the risks of using a UAC, infection is a significant concern when catheters remain in place for more than 10 to 14 days. The UAC becomes colonized by commensal staphylococci within 24 hours of placement, and such colonization may lead to bloodstream infection due to the immature immune system of very low-birthweight (VLBW) infants. The risk for infection is

increased when hyperalimentation fluid is administered through a UAC. Removal of the UAC by the end of the first postnatal week reduces such risk significantly and generally is feasible because most VLBW newborns have improved respiratory status by this time.

Additional risks of inserting and using a UAC include vascular spasm; thrombogenesis; either large-vessel occlusion or embolization of microthrombi in the distal arterial circulation; and damage to the vascular endothelium or further injury leading to a mycotic aneurysm.

Hypoglycemia may occur if the UAC is inserted in the thoracic aorta (between T6 and T10) and fluids that have a high glucose concentration are administered, inducing a hyperinsulinemic response by the pancreas.

Anemia, a common problem in critically ill VLBW newborns, does not result from UAC insertion or use, unless blood loss occurs when the line is accessed, which is rare.

Hyperglycemia is not a complication of inserting or using a UAC. Hypotension is an indication to insert a UAC and monitor blood pressure, not a complication. Thrombocytopenia, not

thrombocytosis, may occur when a thrombus forms on the end of a UAC or elsewhere in the circulation.

References:

Coleman MM, Spear ML, Finkelstein M, et al. Short-term use of umbilical artery catheters may not be associated with increased risk for thrombosis. Pediatrics. 2004;113:770-774. Available at: http://pediatrics.aappublications.org/cgi/content/full/113/4/770

Hermansen MC, Harmansen MG. Intravascular catheter complications in the neonatal intensive care unit. Clin Perinatol. 2005;32:141-156. Abstract available at:

O’Grady NP, Alexander M, Dellinger EP, et al. Guidelines for the prevention of intravascular catheter-related infections. The Hospital Infection Control Practices Advisory Committee, Centers for Disease Control and Prevention. U.S. Pediatrics. 2002;110:e51-e75. Available at:

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Rodriguez RJ, Martin RJ, Fanaroff AA. Respiratory distress syndrome and its management. In: Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant. 8th ed. Philadelphia, Pa: Mosby Elsevier; 2006:1097-1107 Wortham BM, Galtatzes CG, Rais-Bahrami K. Umbilical artery catheterization. In: MacDonald MG, Ramasethu J, eds. Atlas of Procedures in Neonatology. 4th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2007:157-176

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Question: 19

You are evaluating a new patient in your office, a 10-year-old boy who has no significant past medical history or illnesses. His weight and height are both at the 75th percentile. On physical examination, you notice a mild pectus excavatum but no cardiopulmonary abnormalities. When you ask him about it, he replies, "I’ve always had it, and it doesn’t bother me."

Of the following, the MOST appropriate next step in the management of this problem is

A. electrocardiography B. exercise stress testing C. psychological evaluation D. reassurance

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Pectus excavatum is a skeletal abnormality of the chest wall characterized by concavity of the anterior chest. It may occur in isolation or can be associated with other disorders, such as Marfan syndrome and Ehlers-Danlos syndrome, and it is more common in boys. The deformity usually is present in infancy, although symptoms do not present until later in life. Many children are asymptomatic and are not concerned about the cosmetic appearance of the chest, but some children may experience psychological distress about their appearance. Some children

experience symptoms such as dyspnea with exertion, chest or rib pain, and decreased exercise tolerance. Pulmonary function abnormalities, when present, include an obstructive pattern and, less commonly, a restrictive pattern. Cardiac dysfunction due to impaired stroke volume with exercise has been described and is more common in older patients.

Because the boy described in the vignette does not complain of any symptoms and is not psychologically affected by the cosmetic appearance of his chest, only reassurance and observation are necessary. Lateral chest radiographs and chest computed tomography scan can demonstrate the deformity, but such tests generally are not necessary in asymptomatic patients. Similarly, electrocardiography and exercise stress testing are not indicated unless exercise intolerance or dyspnea upon exertion is present. Psychological evaluation could be considered for patients who are very concerned about the cosmetic appearance, and corrective surgery should be considered for those who have severe psychological distress. Pulmonary function, if impaired, often is not improved with surgical correction.

References:

Aronson DC, Bosgraaf RP, Merz EM, van Steenwijk RP, van Aalderen WM, van Baren R. Lung function after the minimal invasive pectus excavatum repair (Nuss procedure). World J Surg. 2007;31:1518-1522. Available at:

http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=17534548 Boas SR. Skeletal diseases influencing pulmonary function. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:1841-1844

Koumbourlis AC, Stolar CJ. Lung growth and function in children and adolescents with idiopathic pectus excavatum. Pediatr Pulmonol. 2004;38:339-343. Abstract available at:

Rowland T, Moriarty K, Banever G. Effect of pectus excavatum deformity on cardiorespiratory fitness in adolescent boys. Arch Pediatr Adolesc Med. 2005;159:1069-1073. Available at: http://archpedi.ama-assn.org/cgi/content/full/159/11/1069

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Question: 20

A nurse practitioner in your clinic has asked you to review the chart of an 11-year-old boy referred from school for evaluation of acanthosis nigricans.

Of the following, the physical examination parameter that is MOST likely to be useful in predicting comorbidities in this patient is

A. blood pressure at the 75th percentile for height B. body mass index at the 95th percentile for age

C. sum of triceps and subscapular skinfold thickness greater than 90% for age D. weight at the 50th percentile and height at the 25th percentile for age E. weight at the 95th percentile and height at the 75th percentile for age