are not effective in the treatment of acute GBS They

are often used in multiple sclerosis.

Pyridostigmine (choice D) and thymectomy (choice E) are not effective in the treatment of acute GBS. They are treatments for myasthenia gravis.

65. The correct answer is D. The patient’s electrocardiogram

shows that she has myocardial ischemia of the left ventri- cle. The diabetes and hypercholesterolemia are risk fac- tors for her coronary artery disease. Treatment must be initiated to decrease her myocardial oxygen demand. Costochondritis (choice A) and musculoskeletal pain

(choice B) are not associated with electrocardiographic

changes.

Myocardial infarction (choice C) is typically associated with either ST elevations or elevated serum markers, neither of which is mentioned in this vignette.

The electrocardiographic findings are consistent with ischemia, not a pulmonary embolism (choice E).

66. The correct answer is C. The most common cause of

microcytic anemia is iron deficiency, and a low serum ferritin confirms that diagnosis. This man has probably been chronically losing blood, and the most likely source is the gastrointestinal tract. Cancer of the right side of the colon is a good bet, and once occult blood is found in the stool, a colonoscopy should follow. Coombs test (choice A) is used for the diagnosis of hemolytic anemia, which is normocytic and does not deplete iron stores.

Hemoglobin electrophoresis (choice B) is used for the diagnosis of thalassemia. The anemia in that disease is indeed microcytic, but the patient would have normal iron stores (normal serum ferritin).

The Schilling test (choice D) has a role when patients have macrocytic anemia, as it helps differentiate perni- cious anemia from intestinal malabsorptive disorders. Anemia caused by renal insufficiency is normocytic, in which case serum creatinine (choice E) would be a use- ful test.

67. The correct answer is A. The history is suggestive of

episodes of hypoglycemia, possibly triggered by an insulinoma. Fasting should induce the symptoms, at which time one could demonstrate the presence of hypoglycemia and high levels of insulin and C peptide. Resolution of the symptoms by glucose administration would then complete the diagnostic “Whipple triad.” CT scan of the pancreas would follow.

Tumors involving the frontal lobe may produce behav- ioral changes, and funduscopic examination (choice B) and MRI (choice D) would be helpful to diagnose that problem. In that case, though, the behavioral changes should be accompanied by persistent headaches, visual changes, and possibly olfactory deficits (Foster Kennedy syndrome). There would be no correlation with fasting or resolution by eating.

Liver failure is a potential cause of hypoglycemia, but the latter would not occur until liver function is severely compromised. The patient would have overt signs of liver failure, rather than a minor, occult deficiency that would be discovered by liver function tests (choice C). If the indicated tests were to show that his symptoms are indeed caused by hypoglycemia, at which time blood levels of insulin were found to be high while the C peptide was low, self-administration of insulin should be suspected. It would be at that point that psy- chiatric evaluation (choice E) would be indicated.

68. The correct answer is C. The presentation is highly sug-

gestive of Zollinger-Ellison (Z-E) syndrome. Further studies after her serum gastrin level is determined might include secretin stimulation test, if needed for confirmation, and CT scan of the pancreas to locate the gastrinoma.

Secretory diarrhea in this setting is part and parcel of Z-E syndrome, and pathology in the intestinal mucosa need not be sought (choice A).

Biopsy of the ulcer (choice B) is dangerous and unnec- essary. Biting into an ulcer that recently bled is an invi- tation to rebleeding, and ascertaining if the ulcer is benign or malignant is indicated in the case of gastric ulcers but is not pertinent for duodenal ulcers.

At some point, serum calcium (choice D) needs to be measured. Gastrinomas may coexist with parathyroid adenomas. It would not be the first test needed, however, before the presence of Z-E has been established. Upper gastrointestinal series with barium (choice E) does not add any information to that already provided by the endoscopy.

69. The correct answer is B. This man has massive gas-

trointestinal bleeding, and the nasogastric aspirate indi- cates that it is coming from beyond the ligament of Treitz. Approximately 70% of patients who bleed from a source distal to that landmark do so from diverticulo- sis. Approximately one quarter of those present with massive bleeding. The offending diverticula are usually in the right colon and thus are not visible to a proc- tosigmoidoscopic examination. The usual patient with this presentation is old enough to have diverticulosis. All the numbers quoted fit this particular case.

Colon cancer (choice A) also occurs in older people. It is also a frequent source of bleeding, but typically the bleeding is not massive. Furthermore, the left side of the colon hosts cancers more frequently than the right. This man could be bleeding from a colonic cancer, but obvi- ously that would not be the most likely situation.

Duodenal ulcer (choice C) has been excluded by the nasogastric aspirate. Upper gastrointestinal sources always have to be considered when people bleed per rectum (a common dictum says that a common cause for lower gastrointestinal bleeding is in fact upper gas- trointestinal bleeding), and that is why the nasogastric aspiration is done. Once one sees green fluid without blood, however, one stops thinking of upper gastroin- testinal lesions.

Inflammatory bowel disease (choice D) can bleed, but that source is way down on the list of possibilities. Portal hypertension (choice E) can produce massive bleeding. Typically, however, it is by way of esophageal varices (which have been ruled out by the nasogastric aspirate) or hemorrhoids (which have been ruled out by direct examination of the anorectal area).

70. The correct answer is A. Although this patient has the

clinical presentation of diverticulitis, the key point is that the patient was recently treated with gentamicin and is therefore at risk for nephrotoxicity. This takes the form of acute tubular necrosis and may either be olig- uric or nonoliguric. Patients with the nonoliguric form generally recover their renal function if the aminogly- coside is discontinued and the patient is adequately hydrated.

Diverticulitis (choice B) has no direct effect on renal function. Theoretically, patients with diverticulitis without septic shock may develop renal insufficiency, but there is no evidence of that scenario here.

Left ureteral obstruction (choice C) may occur in a patient with sigmoid diverticulitis but would not cause renal insufficiency unless the patient also had right kid- ney dysfunction.

Pyelonephritis (choice D) is not described by the phys- ical and CT scan findings in this patient, and unilateral pyelonephritis would not cause renal insufficiency. There is no evidence by physical examination that this patient is in shock (choice E).

71. The correct answer is D. This previously healthy young

woman has significant systolic and diastolic hyperten- sion. The classic clue here is an upper abdominal bruit, which suggests the diagnosis of renovascular hyperten- sion. In a young woman, the diagnosis of renovascular hypertension is usually due to fibromuscular dysplasia, which is usually unilateral and unifocal.

Although aortic dissection (choice A), coarctation of the aorta (choice B), hypertrophic cardiomyopathy (choice