Laboratory and Diagnostic Testing. Everything you need to know

Laboratory and Diagnostic Testing

Everything you need to know

Objectives

• Discuss the use of common tests and procedures

• Identify abnormal findings of commonly used tests and procedures

• Describe nursing care of patients undergoing diagnostic procedures

• Explain reasons for preparation of patients for tests and procedures

Specimen Collection and Diagnostic Exams

• Explain the rationales for collection of each specimen listed: urine, stool, sputum

• Discuss guidelines used for obtaining throat and wound cultures

• State appropriate labeling for a collected specimen

• List the proper steps for measuring blood glucose levels

• Discuss the procedure for obtaining a sputum specimen

• List the proper steps when obtaining urine specimens

Before You Start

• Wash your hands

• Wear gloves

• Label all containers with appropriate patient identifiers

• Date

• Time

• Initial

• Place specimens in proper containers/

biohazard bags

• Have consents signed for invasive procedures

Blood Glucose Monitoring

Normal Blood glucose: 75- 115

Monitor glucose levels to manage insulin administration

Patient teaching

Wash patient’s hands

Use side of the finger not the pad Wipe off first drop of blood

Place large drop of blood on test strip Document procedure

Urine Specimens

• Test for infection

• Assess metabolic function

• Assess kidney function

• Test for drugs/ alcohol

General characteristics and measurements:

Color: pale yellow to amber Appearance: clear to slightly hazy

Specific Gravity: 1.010- 1.030

pH: 4.5 - 8 (average pH between 5 and 6) Volume: 1500cc/24 hours (adult)

Chemical determinations:

Glucose: negative Ketones: negative

Blood: negative Protein: negative

Nitrate for bacteria: negative Leukocyte esterase: negative Microscopic exam of sediment:

Casts: negative (occasional hyaline casts) Red blood cells (RBCs): negative or rare White blood cells (WBCs): negative or rare

Crystals: negative Epithelial cells: few

Urine collection technique for women

Wash hands with soap and water

Spread labia with 1 hand and hold apart for collection Use three povidone-iodine swabs to clean area

Wipe down one side, front to back, with one swab Wipe down other side, front to back, with second

swab

Wipe down center, front to back, with last swab Dry area with sterile gauze

Void into toilet for a few seconds and then stop Restart urine stream and collect in sterile container

Cap and avoid touching inside of container

Urine collection technique for men

Wash hands with soap and water Retract foreskin if needed

Use povidone-iodine swabs to clean tip of penis Clean glans penis

Clean urethral opening Dry area with sterile gauze

Void into toilet for a few seconds and then stop Restart urine stream and collect in sterile container

Cap and avoid touching inside of container

Urine Collection from a catheter

• Never open the closed system

• Don’t take urine from the collection bag

• Cleanse collection port with alcohol swab

• Use sterile needle and syringe

• Transfer urine to specimen container

• Dispose of syringe in sharps container

Lab requirements

• At least 10 ml

• First voided morning urine is more

concentrated—abnormalities are easier to detect

24 Hour Urine Collection

• Reveals how kidneys adapt to physiologic needs over time

• Begin test after patient empties bladder

• Collect all urine over the next 24 hours

• Collection may need to be chilled

Sputum Collection

• Gather sterile specimen container

• Explain what is needed to patient

• Have patient deep breathe and cough

• Expectorate into container

• Need sputum NOT saliva

• If patient is unable to expectorate, suctioning may be required

Stool guaiac test

• detects the presence of hidden (occult) blood in the stool

• red meat, any blood-containing food, cantaloupe, uncooked broccoli, turnip,

radish, or horseradish eaten 3 days prior to the test may give false positive

• Colon polyps

• Colon cancer or other gastrointestinal (GI) tumors

• Esophagitis

• Gastritis

• GI trauma or bleeding from recent GI surgery

• Hemorrhoids

• Inflammatory bowel disease

• Peptic ulcer

• Angiodysplasia of the GI tract

• GI infections

• Esophageal varices and portal hypertensive gastropathy

Stool

• Ova and parasites

• Culture C. dificil

• For occult blood only a thin smear is needed

Throat Culture

•   Not all bacteria cause illness.  Actually the

mouth normally contains many types of bacteria which would contaminate the throat culture

sample.  

• The swab is taken from the tonsils to isolate primarily infecting bacteria. 

• Even though care is taken not to touch the teeth, roof of the mouth, or tongue when the swab is

taken, other bacteria are nevertheless apt to be present in the sample.

Throat cultures

Wound culture

• To collect a tissue or fluid sample from a wound, a sterile swab is inserted into the wound. It may be necessary to press

around the wound and gently turn the

swab to collect as much tissue or fluid as possible. The swab is then placed into

either an aerobic or anaerobic culture tube or both, depending on the type of

organism suspected

Radiologic Exams

• The chest x-ray is performed to evaluate the lungs, heart and chest wall.

• A chest x-ray is typically the first imaging test used to help diagnose symptoms such as:

• shortness of breath

• a bad or persistent cough

• chest pain or injury

• fever.

• Physicians use the examination to help diagnose or monitor treatment for conditions such as:

• pneumonia

• heart failure and other heart problems

• emphysema

• lung cancer

• Confirm tube placement

CT Scans

• Becoming the preferred method of

diagnosing diseases of bowel and colon

• May require pt to be NPO or take contrast

• Know patient allergies to contrast or shellfish

• Is patient taking metformin or glucophage

Echocardiogram

Endoscopy

• Bronchoscopy

• Colonoscopy

• Esophogogastroduodenoscopy (EGD)

Colonoscopy

• Bowel must be empty

• Used to visualize inside of colon

• Screen for polyps, colon cancer, lower GI bleeding

Nursing Considerations

• Make sure patient has been NPO

• Make sure patient has finished bowel prep

• Patient education

• Reassurance

• IV

• Pain control

• Follow-up

• Usually done while

patient is sedated but not completely anesthetized.

• LVN assists MD with procedure, handling equipment, moving patient, etc.

EGD

• NPO after midnight

• Patient education

• IV, reassurance

• Visualize esophagus and stomach

• Screen for ulcers, esophageal varices

• Open blocked esophagus

After Care

• Monitor until patient is awake

• Gag reflex intact

• No pain

• Patient education

Thoracentesis

• Assist with Positioning Reassurance Aftercare

Laboratory Tests

• Blood tests used to :

– Diagnose illness – Monitor drug levels

– Monitor disease and healing

Common Lab Orders

• CBC

• H&H

• BMP

• CMP

• BNP

• Lytes

• Mg+

• Ca+

• Phos

• Trop

• CK

• UA

• HbA1C

• ABG’s

• BG

• LFT

• Amylase

• BUN/Creat

Amalayse

• The blood test for amylase is used to diagnose pancreatitis (swelling of the pancreas) and other pancreatic diseases. The near-immediate rise of amylase at the beginning of a pancreatitis

attack, and its fall after about 2 days, helps to pinpoint this diagnosis.

Amylase is also used (to a lesser extent) in the diagnosis and follow-up of cancer of the

pancreas, ovaries, or lungs; gallbladder attack;

and mumps.

CBC

• The CBC is used as a broad screening

test to check for such disorders as anemia , infection, and many other diseases. It is actually a panel of tests that examines

different parts of the blood

• White blood cell (WBC) count is a count of the actual number of white blood cells per volume of blood. Both increases and decreases can be significant.

• White blood cell differential looks at the types of white blood cells present. There are five different types of

white blood cells, each with its own function in protecting us from infection. The differential classifies a person's white blood cells into each type: neutrophils (also known as segs, PMNs, grans), lymphocytes, monocytes,

eosinophils, and basophils

• Normal: 4.5 –11.0 x10⁹

• Red blood cell (RBC) count is a count of the actual number of red blood cells per volume of blood. Both increases and

decreases can point to abnormal conditions

• Decreased with anemia

• Increased with dehydration or over- production

• Hemoglobin measures the amount of oxygen-carrying protein in the blood

• Normal value:

– Men: 14 – 18

– Women: 12 – 16

• Hematocrit measures the amount of space red blood cells take up in the blood. It is

reported as a percentage.

• Normal:

– Men: 40 --54%

– Women: 37 –47%

Platelets

• The platelet count is the number of platelets in a given volume of blood. Both increases and

decreases can point to abnormal conditions of excess bleeding or clotting. Mean platelet

volume (MPV) is a machine-calculated measurement of the average size of the platelets. New platelets are larger, and an

increased MPV occurs when increased numbers of platelets are being produced. MPV gives the doctor information about platelet production in the bone marrow.

• Normal: 130,000—400,000

• Erythrocyte Sedimentation rate tests how

:

quickly RBC’s settle in a test tube in one hour.

• Increased ESR indicative of inflammation

• Males younger than 50:0–15 millimeters per hour (mm/hr)

• Males 50 and older:0–20 mm/hr

• Females younger than 50:0–25 mm/hr

• Females 50 and older:0–30 mm/hr

Lytes

• Electrolytes are salts that conduct electricity and are found in the body fluid, tissue, and blood.

Examples are chloride, calcium, magnesium, sodium, and potassium. Sodium (Na+) is

concentrated in the extracellular fluid (ECF) and potassium (K+) is concentrated in the

intracellular fluid (ICF). Proper balance is

essential for muscle coordination, heart function, fluid absorption and excretion, nerve function,

and concentration.

Magnesium

• Magnesium is needed for more than 300 biochemical reactions in the body. It helps maintain normal muscle and nerve function, keeps heart rhythm steady, supports a healthy immune system, and keeps bones strong.

Magnesium also helps regulate blood sugar levels, promotes normal blood pressure, and is known to be involved in energy metabolism and protein synthesis . There is an increased interest in the role of magnesium in preventing and managing disorders such as

hypertension, cardiovascular disease, and diabetes.

Dietary magnesium is absorbed in the small intestines.

Magnesium is excreted through the kidneys.

Magnesium

• Normal: 1.8-2.4 mEq/L

• 40-60% stored in muscle and bone, 1/3 bound to plasma proteins

• Hypermangesemia: renal failure, excess intake (usually through antacids), adrenal insufficiency.

• Excess causes: skeletal smoot muscle

contraction, excess nerve function, loss of DTR, N/V, bradycardia, resp. distress

Magnesium

• Hypomagnesemia <1.5 mEq/L

• Malnutrition, malabsorption, renal tubular dysfunction, loop diuretics

• Causes: Behavioral changes, increased reflexes, muscle cramps, ataxia,

nystagmus, convulsions, tachycardia, hypotension

Potassium

• Normal 3.5 -5.5

• Kidneys are the most efficient regulator of potassium balance

• 98% of total body K+ is located in the cells

• Regulates muscle activity via maintenance of electrical conduction

• Regulates acid/base balance

• Required for deposition of glycogen and glucose in liver and skeletal muscle cells

Hypokalemia

Etiology: Diuretics, diarrhea, vomiting,

malnutrition, renal losses associated with

glycosuria, ketonuria, hyperaldosteronism. K+

shifts into cells with alkalosis insulin administration

S/S: confusion; rapid, weak, irregular pulse;

hypotension, anorexia, decreased reflexes,

muscle weakness, paresthesia, EKG changes

Hyperkalemia

• Causes: renal failure, cell damage from burns, injuries, chemotherapy, acidosis, DM

• S/S: Weakness, malaise, nausea, diarrhea, muscle irritability,

oliguria,bradycardia, EKG changes

Sodium

• Normal: 136-145

Sodium is the main cation (positive ion) that circulates in the body fluids outside the cells.

It is a critical component in blood pressure maintenance.

Sodium is also essential for the proper workings of nerves and muscles.

Hyponatremia

• Burns

• Vomiting and diarrhea

• Use of diuretics ("water pills"), especially of the type known as thiazide diuretics

• Certain kidney diseases

• Liver cirrhosis

• Congestive heart failure

• Syndrome of inappropriate antidiuretic hormone secretion (SIADH ,

• S/S: fatigue, headache, restlessness, nausea, muscle cramps, disorientation, coma, seizures, death

Hypernatremia

Findings Details

Cognitive dysfunction Lethargy, obtundation, confusion Abnormal speech

Irritability

Dehydration or volume-associated findings

Orthostatic blood pressure changes Tachycardia

Oliguria

High BUN-to- creatinine ratio Dry axillae

O

t h e r c l i n i c a l f i n d i n g s Weight loss

Generalized weakness Seizures

Nystagmus Myoclonic jerks

• Risk factors for hypernatremia

– Age older than 65 years

– Mental or physical disability

– Hospitalization (intubation, impaired cognitive function)

– Residence in nursing home – Inadequate nursing care

– Urine concentrating defect (diabetes insipidus) – Solute diuresis (diabetes mellitus)

– Diuretic therapy

Calcium

• Normal 9-10.5

• Function: Promotes and regulates neuromuscular and enzyme activity, coagulation

Hypocalcemia

• Causes: parathyroid insufficiency,

hypomagnesemia, hyperphosphatemia, laxatives, malabsorption, malnutrition, diarrhea, vitamin D deficiency

• S/S: circumoral and peripheral

paresthesias, muscle twitching, facial spasm, muscle cramping, seizures, dysrhythmias

Hypercalcemia

• Hypercalcemia is a higher than normal level of calcium in the blood.

The most common cause is an overactive parathyroid gland

(hyperparathyroidism). The parathyroid glands, which are located below the thyroid gland, regulate calcium in your body.

• Other causes of hypercalcemia include:

• Certain medications, such as lithium or thiazide diuretics

• Certain cancers, including breast, lung and certain blood cancers

• Sarcoidosis, an inflammatory disorder

• Excessive intake of calcium or vitamin D supplements

• Familial hypocalciuric hypercalcemia, a genetic disorder

• Dialysis for chronic kidney failure

• Adrenal gland failure

• Overactive thyroid (hyperthyroidism)

Hypercalcemia

• Nausea/vomiting

• Excessive thirst

• Constipation

• Abdominal pain

• Muscle weakness

• Lethargy and fatigue

• Confusion

• May cause kidney stones and dysrhythmias

• Stain urine for stones

• Send stones to lab for analysis

Chloride

• Normal 98-106

• Functions: Varies inversely with

bicarbonate, maintain acid/base balance, associated with low Na+ and low K+ levels

Hyperchloremia

• Occurs when there is too much NA+ or too little bicarbonate

• No specific symptoms are associated with too much chloride

Hypochloremia

• Causes: Hyponatremia or elevated bicarbonate levels as in metabolic

alkalosis. May develop with vomiting and the loss of hydrochloric acid. Cystic

fibrosis is characterized by hypochloremia.

BUN

• Normal: 10-20mg/dL

• Reflects protein intake, liver function, kidney

excretory capacity. Elevation without concurrent creatinine elevation is indicative of dehydration

• Increases: renal disease, inadequate renal blood flow, urinary tract obstruction, protein catabolism as seen in burns and starvation.

• Decreases: severe liver failure, malnutrition, overhydration,

Creatinine

• Normal: <1.5 mg/dL

• Excreted by kidneys

• Increase: Renal disease, DKA, starvation, muscle disease, hyperthyroidism,

diuretics, barbiturates

BNP

• Brain Natriuretic peptide

• Regulates sodium excretion (natriuresis), diuresis, vasodilation leading to large

volume of dilute urine

BNP levels below 100 pg/mL indicate no heart failure BNP levels of 100-300 suggest heart failure is present BNP levels above 300 pg/mL indicate mild heart failure BNP levels above 600 pg/mL indicate moderate heart failure.

BNP levels above 900 pg/mL indicate severe heart failure.

CPK

• Creatinine phosphokinase

• An enzyme found in muscle tissue

• Elevated levels indicate muscle injury

• CK-MB elevations indicate cardiac muscle injury

• CK-MM—skeletal muscle

• CK-BB brain tissue

Troponin

• Troponin I: protein released by heart muscle is a specific marker for cardiac injury

Specimen Collection

Correctly Label Specimens

Patient Teaching

• About the procdure and what to expect

• Pain control

• Home care

Documentation

• Understand the significance of the tests

• Document how patient tolerated tests

• Document any patient teaching

• Report and document abnormalities