Chem

Given the following data, determine the CV: Monthly mean = 140 mmol/L SD = 1.6 Variance = 2.6 0.4% 1.1% 1.8% 3%

1.1%

At a normal physiological pH, what is the ratio of bicarbonate to dissolved CO2 in arterial blood? 10:1 20:1 1:4 1:10

20:1

In a patient with primary ovarian failure, the mid-menstrual estrogen is low, and the LH level is High. Low. Unaffected. Variable.

High

Given the following results, calculate the concentration of glucose in the specimen: Absorbance of standard = 0.42 Absorbance of sample = 0.32 Concentration of glucose standard = 100 mg/dL Volume of standard and sample = 10 µL Volume of reagent = 0.5 mL 76 mg/dL 131 mg/dL 380 mg/dL 672 mg/dL

76 mg/dL

At what time of the day would you expect a patient's plasma total cortisol to be the highest? 6:00 a.m. 11:00 a.m. 9:00 p.m. 11:00 p.m.

6:00 a.m.

A pregnant woman is seen in the emergency department at 32 weeks' gestation. A fetal fibronectin test is performed and is negative. This indicates A high probability of preterm delivery. A low probability of preterm delivery. A low probability of hemolytic disease of the newborn. A low probability of toxemia of pregnancy.

A low probability of preterm delivery.

In the enzymatic method for measuring urea, the coupling reaction is A negative rate reaction measuring the production of NAD+. A positive rate reaction measuring the CO2 produced. A peroxidase reaction. Linked to the oxidation of lactate to pyruvate.

A negative rate reaction measuring the production of NAD+.

Which of the following enzymes are the best markers for obstructive jaundice? AST and ALP Amylase and lipase ALP and acid phosphatase ALP and GGT

ALP and GGT

A patient has an elevated AST, bilirubin, and LD. Which test is most likely to be elevated? Uric acid ALT Creatinine CK

ALT

A patient with liver disease has serum transaminases that are 20-fold higher than the URL. You would expect ALP to be greater than ALT. ALT to be greater than AST. Direct bilirubin to be more than 50% of the total bilirubin. GGT to be greater than AST.

ALT to be greater than AST.

Which of the statements below best describes the clinical utility of ALT? ALT/AST is greater than 1 in viral hepatitis. ALT elevations are usually 2 to 5x normal in acute hepatitis. ALT levels are the highest in liver carcinoma. ALT is the best marker for alcoholic liver disease.

ALT/AST is greater than 1 in viral hepatitis.

Which of the following substances is a chemiluminescent molecule? 4-Methylumbelliferyl phosphate (4-MUP) Acridinium Chlorophenol red β-galactopyranose p-Nitrophenyl phosphate

Acridinium

A patient's liver function tests give the following results: Aspartate aminotransferase (AST) = 630 IU/L Alanine aminotransferase (ALT) = 802 IU/L Alkaline phosphatase (ALP) = 160 IU/L γ-Glutamyltransferase (GGT) = 256 IU/L Lactate dehydrogenase (LD) = 235 IU/L What is the most likely cause of these results? Biliary carcinoma Hemolytic anemia Alcoholic liver disease Acute hepatitis

Acute hepatitis

A patient has a serum amylase that is fivefold greater than the URL 6 hours after an episode of acute abdominal pain. The serum amylase decreases by 25% 1 day later, but urinary amylase and the amylase:creatinine (A:C) clearance ratio remain elevated. These results point to Acute pancreatitis. Appendicitis. Chronic active hepatitis. Mumps.

Acute pancreatitis.

What is the most likely cause of a GGT result that is five times the URL in a patient who has a twofold elevation of ALP and transaminases? Alcoholic liver disease Bone disease Obstructive jaundice Viral hepatitis

Alcoholic liver disease

The biuret method is based on the reaction of proteins with which reagent? Alkaline copper sulfate Alkaline ferricyanide Alkaline nitroprusside Bromocresol purple

Alkaline copper sulfate

Which tumor marker level is usually increased in liver cancer? Alpha fetoprotein CA 19-9 CA-27.29 CEA

Alpha fetoprotein

A CRP (ultrasensitive) concentration of 12 mg/L (URL = 3.1 mg/L) is evidence of which condition? An increased risk of myocardial infarction A myocardial infarction within the last 6 hours Skeletal muscle injury A reinfarction after a recent myocardial infarction

An increased risk of myocardial infarction

A C-reactive protein (CRP) (high sensitivity) concentration more than 10 mg/L is evidence of An unstable coronary plaque. A myocardial infarction within the last 6 hours. An episode of ischemia. A reinfarction after a recent myocardial infarction.

An unstable coronary plaque.

Which of the following conditions would cause hyponatremia? Alkalosis Burns Cushing disease Hyperpituitarism

Burns

Situation: A complexometric assay for calcium is calibrated with a 10.0 mg/dL standard that has been left out for too long. Owing to evaporation, its concentration increased by 10%. What effect will this have on the concentration of the controls? Both controls will be too high. The normal control will not be affected because it is close to the calibration set point. The high control will be too high and the low control will be too low. Both controls will be too low.

Both controls will be too low.

At steady-state blood concentration, which condition is true? Drug absorbed equals drug eliminated. Drug distribution changes. Drug elimination reaches saturation. Bioavailable fraction decreases.

Drug absorbed equals drug eliminated.

Which tumor marker is used to monitor for recurrence of pancreatic and stomach cancer? CA 125. CA 19-9. CA 15-3. CA 27.29.

CA 19-9.

Which analyte is used as a marker for recurrence of breast cancer? ALP CA 27.29 Cathepsin D Neuron-specific enolase

CA 27.29

Which of the following is the best analyte to monitor for recurrence of ovarian cancer? Cancer antigen (CA) 125 CA 15-3 CA 19-9 Carcinoembryonic antigen (CEA)

Cancer antigen (CA) 125

Which component of an atomic absorption spectrophotometer eliminates interference from light emitted by excited atoms? Atomizer Chopper Hollow cathode lamp Monochromator

Chopper

Which of the following conditions is most likely to cause an abnormally low albumin/globulin (A/G) ratio? Chronic liver disease Dehydration Hypogammaglobulinemia Fever

Chronic liver disease

A patient has a BUN of 80 mg/dL. Which other analyte is likely to be elevated? Bilirubin Creatinine Glucose Sodium

Creatinine

What is the most likely cause of an increased osmolal gap in an emergency department setting? Hypoxia Myocardial infarction Drug or alcohol abuse Dehydration

Drug or alcohol abuse

Which of the following is likely to produce an elevated value of serum sodium? Addison disease Diabetes insipidus Hypoparathyroidism Prerenal failure

Diabetes insipidus

A patient's fasting glucose is 130 mg/dL on two consecutive occasions. This is consistent with a diagnosis of Diabetes mellitus. Hyperglycemia caused by nondiabetes (e.g., medications). Hyperthyroidism. Impaired glucose tolerance (IGT).

Diabetes mellitus.

Which condition most often gives the highest elevation of total CK? Cerebrovascular accident Duchenne muscular dystrophy Malignancy Myocardial infarction

Duchenne muscular dystrophy

Which method is the most useful when screening for errors of amino and organic acid metabolism? Two-dimensional thin-layer chromatography Gas chromatography Electrospray ionization tandem mass spectroscopy Inductively charged coupled mass spectroscopy

Electrospray ionization tandem mass spectroscopy

Backward movement of gamma globulins in agarose gel caused by movement of water toward the cathode is called Capillary electrophoresis. Discontinuous electrophoresis. Electroendosmosis. Wick flow

Electroendosmosis.

Which statement best describes chemiluminescence? Emission of ultraviolet (UV) light when atoms are excited by other atoms Emission of light when molecules are excited by a chemical reaction Absorption of light when molecules are excited by UV light Emission of long wavelength light when molecules are excited by short wavelength light

Emission of light when molecules are excited by a chemical reaction

Total protein and albumin measurements are performed on a sample, and the following results are obtained: Total protein = 7.1 g/dL Albumin = 6.9 g/dL On the basis of these results, you would suspect Dehydration in the patient. Error in the albumin measurement. Specimen misidentification. The patient has hepatic failure.

Error in the albumin measurement.

In an emergency department, which condition most often results in an increased osmolal gap? Cardiac arrest Diabetes mellitus Ethanol intoxication Renal failure

Ethanol intoxication

A laboratory measures total bilirubin by the Jendrassik-Grof bilirubin method with sample blanking. What would be the effect of moderate hemolysis on the test results? Falsely elevated owing to optical interference No effect owing to compensating errors No effect owing to blanking Falsely low owing to inhibition of the diazo reaction

Falsely low owing to inhibition of the diazo reaction

According to the current American Diabetes Association (ADA) guidelines, which individual's result is above the cutpoint for diabetes mellitus? Fasting glucose = 127 mg/dL Casual nonfasting glucose = 145 mg/dL 2-Hour postprandial glucose = 185 mg/dL 2-Hour oral glucose tolerance (75 g load) = 190 mg/dL

Fasting glucose = 127 mg/dL

Which group of the following chemicals is considered carcinogenic and classified as harmful in the clinical laboratory? 95% ethanol and 95% methanol 50% sodium hypochlorite and 100% ethanol Formaldehyde and xylene Sodium iodide and sodium acetate

Formaldehyde and xylene

Arterial Po2 is a sensitive and specific measure of Gas exchange efficiency. The amount of oxygen carried by the blood. The amount of oxygen delivered to the tissues. The oxygen content of the blood.

Gas exchange efficiency.

Which of the following substances inhibits release of GH? Arginine Glucose Growth hormone-releasing hormone (GhRH) Insulin

Glucose

Which condition is caused by defective transport of bilirubin across the microsomal membrane of the hepatocyte and reduced conjugation giving rise to mild jaundice? Crigler-Najjar syndrome type I Dubin-Johnson disease Gilbert disease Neonatal physiological jaundice

Gilbert disease

A jaundiced patient has these laboratory test results: Direct bilirubin = 0.1 mg/dL Indirect bilirubin = 2.8 mg/dL Total bilirubin = 2.9 mg/dL Urine bilirubin = negative ALP = 30 U/L AST = 35 U/L What disorder is the most likely cause? Bone cancer Hemolytic anemia Hepatitis Obstructive jaundice

Hemolytic anemia

The term "first-pass hepatic metabolism" refers to Metabolism of 100% of drug after one pass through the liver. Hepatic metabolism of some drug before it reaches the general circulation. Release of drug metabolites by the liver. Excretion of drug into the bile without biotransformation.

Hepatic metabolism of some drug before it reaches the general circulation.

Which of the following would most likely cause a decreased (less than 6 mmol/L) anion gap? Diabetic ketoacidosis Hyperalbuminemia Hypercalcemia Hypomagnesemia

Hypercalcemia

What is the primary mechanism of compensation expected for a patient with metabolic acidosis? Increased retention of bicarbonate Hyperventilation Hypoventilation Increased renal acid excretion

Hyperventilation

A patient has the following arterial blood gas results: pH = 7.52 Pco2 = 20 mm Hg Po2 = 100 mm Hg HCO3- = 24 mmol/L The results are most likely due to Improper specimen collection. Prolonged storage. Hyperventilation. Hypokalemia.

Hyperventilation.

Primary hyperparathyroidism results in which of the following lab values? Increased calcium and inorganic phosphorus Decreased calcium and inorganic phosphorus Increased calcium and decreased inorganic phosphorus Decreased calcium and increased inorganic phosphorus

Increased calcium and decreased inorganic phosphorus

Which statement best describes the use of the microalbumin test? Increased urine microalbumin correlates with an increased risk of glomerular disease in persons with diabetes. Microalbumin is used to identify persons with total calorie malnutrition. Microalbumin is a low molecular catabolic product of albumin produced in acute renal failure. Microalbumin levels above 25 μg/mg creatinine signify end-stage renal failure.

Increased urine microalbumin correlates with an increased risk of glomerular disease in persons with diabetes.

A person has a glycosylated hemoglobin of 12%. Which is the most accurate interpretation? Normal control over blood glucose Insufficient control over blood glucose Indeterminate without the fasting glucose Indeterminate without serial measurements

Insufficient control over blood glucose

Which statement regarding plasma myoglobin is true? It is elevated 3 to 4 hours after myocardial infarction, but is not specific for a myocardial infarction. A 10-fold increase in serum myoglobin is diagnostic of a myocardial infarction. Myocardial infarction can be ruled out if the myoglobin does not exceed 2,000 μg/L at the time of testing. Slight hemolysis can interfere with the measurement.

It is elevated 3 to 4 hours after myocardial infarction, but is not specific for a myocardial infarction.

Situation: John Doe has an HDL cholesterol of 30 mg/dL and George Smith has an HDL cholesterol of 50 mg/dL. Given that all other markers for CAD are equivalent for both, what conclusion can you draw about their relative risk of CAD? John Doe has a higher risk. George Smith has a higher risk. Risk is low for both. Risk is high for both.

John Doe has a higher risk.

When is a trough sample for therapeutic drug monitoring collected? Just before the next dose is given After the dose has been absorbed and distributed 1 hour after administration of an oral dose Before any drug therapy is initiated

Just before the next dose is given

Which lipoprotein carries most of the plasma cholesterol? VLDL LDL HDL Chylomicrons

LDL

In which of the following conditions would an increase in the anion gap be expected? Diarrhea Hypercalcemia Hyponatremia Lactate acidosis

Lactate acidosis

Which of the following analytes is the first to become abnormal and return to normal after a myocardial infarction? CK-MB AST Myoglobin Troponin T

Myoglobin

Which of the following conditions is the most likely to cause an elevated serum uric acid? Chronic liver disease Emphysema Heart failure Leukemia

Leukemia

In a competitive chemiluminescent assay for a tumor marker Concentration is linearly and directly related to signal. Light emission is inversely related to concentration and nonlinear. The signal is inversely related to concentration and linear so that a single calibrator can be used. The light emission is continuous rather than discontinuous.

Light emission is inversely related to concentration and nonlinear.

Which of the following lipoproteins is implicated as a risk factor for coronary artery disease (CAD) independently of its cholesterol content? Lipoprotein (a) Intermediate-density lipoprotein (IDL) Small LDL VLDL

Lipoprotein (a)

A patient has a serum K value of 6.5 mmol/L, chloride 101 mmol/L, creatinine 1.1 mg/dL, and inorganic phosphorus 5.5 mg/dL. Which test is most likely to be elevated as well? Calcium Cholesterol Magnesium Sodium

Magnesium

In the Jaffe reaction for creatinine, interference caused by protein can be eliminated by Measuring the timed rate of creatinine picrate formation. Adding ascorbic acid to the reagent. Reading the absorbance at 600 nm. Performing a serum blank.

Measuring the timed rate of creatinine picrate formation.

Given the serum protein electrophoresis pattern shown, which transaminase results would you expect? Within normal limits for both Marked elevation of both (10-fold to 50-fold normal) Marked elevation of AST but normal ALT Mild-to-moderate elevations of both (three- to fivefold normal)

Mild-to-moderate elevations of both (three- to fivefold normal)A patient has the following plasma results:

In general, the use of tumor marker assays has the most clinical utility in Screening for cancer. Early diagnosis of malignancy. Monitoring for recurrence. Predicting outcome of treatment.

Monitoring for recurrence.

In reverse phase high-performance liquid chromatography (HPLC), the mobile phase is More polar than the stationary phase. Less polar than the stationary phase. Made up of at least two solvents mixed in different proportions. Introduced into the column in pulses.

More polar than the stationary phase.

Which condition gives rise to an increase in total protein but causes a decrease in albumin? Diabetes insipidus Chronic liver disease Multiple myeloma Nephrotic syndrome

Multiple myeloma

CSF protein electrophoresis is used most often to aid in which diagnosis? Meningitis Multiple myeloma Multiple sclerosis (MS) Subarachnoid hemorrhage

Multiple sclerosis (MS)

Extremely high plasma levels of ALP in the absence of an elevated direct bilirubin, GGT, or transaminases would most likely indicate which condition? Biliary cirrhosis Hypoparathyroidism Muscular dystrophy Paget disease or bone malignancy

Paget disease or bone malignancy

Which of the following statements best characterizes non-insulin-dependent diabetes mellitus (type 2)? Insulin administration is required to control hyperglycemia. Usually occurs in individuals younger than 40 years. Ketosis develops under basal conditions. Patients are usually obese.

Patients are usually obese.

Which of the following is the most sensitive type of photodetector? Barrier layer cell Photodiode Photomultiplier tube Phototube

Photomultiplier tube

A blood sample collected in a gray-top tube gave the following results: Glucose = 94 mg/dL Blood urea nitrogen (BUN) = 6 mg/dL Creatinine = 2.7 mg/dL What is the most appropriate course of action? Report these results Repeat the BUN on a new sample with no additive Repeat the creatinine Report only the BUN and glucose

Repeat the BUN on a new sample with no additive

Which of the following tests is most affected by hemolysis? Calcium Chloride Potassium Sodium

Potassium

A patient presents with a 24-hour urinary free cortisol that is below the reference range. The patient's plasma ACTH is elevated. Other pituitary hormones are normal. This indicates A falsely elevated urinary free cortisol level. Cushing syndrome. Primary Addison disease. Secondary Addison disease.

Primary Addison disease.

A patient has a high free T3 and a TSH level of 0.02 mU/mL (reference range 0.40 to 4.0 mU/mL). These results point to which condition? Primary hyperthyroidism Primary hypothyroidism Secondary hyperthyroidism Laboratory error in the TSH measurement

Primary hyperthyroidism

Which of the following conditions is likely to produce elevated serum potassium? Cushing syndrome Diarrhea Parathyroid disease Renal failure

Renal failure

A blood lactic acid sample was collected in a gray-top tube that was drawn after sequentially filling red-top, green-top, and purple-top tubes. The lactate level was 30 mg/dL. A second lactic acid sample was ordered 1 hour later and drawn in a gray-top tube without filling any other tubes. The result was 20 mg/dL. What is the most likely explanation of this result? The wrong type of additive was used. Prolonged hemostasis falsely elevated the first result. Result represents normal physiological variation. The patient was misidentified.

Prolonged hemostasis falsely elevated the first result.

A blood sample for glucose assay is collected at 4 p.m. and left at room temperature until 5 p.m. A glucose oxidase procedure is performed at 5:30 p.m. immediately after the serum has been separated from the cells. What statement best predicts the results of the test? Results will be elevated owing to hemolysis. Results will be accurate because the method is not affected by hemolysis. Results will be about 20 mg/dL too low because glucose oxidase methods underestimate glucose concentration. Results will be about 7% too low because glucose is used by cells.

Results will be about 7% too low because glucose is used by cells.

A negative test result for B-type natriuretic peptide (BNP) is used to Rule out essential hypertension. Rule out a recent myocardial infarction. Rule out congestive heart failure. Identify patients with unstable angina.

Rule out congestive heart failure.

Stray light would cause the greatest error in which of the following samples? Sample 1—50% transmittance (T) Sample 2—25%T Sample 3—20%T Sample 4—10%T

Sample 4—10%T

A patient's CK-MB is 3 µg/L at admission, and the total CK is 174 U/L. Four hours later, the CK-MB is 3 µg/L and the total CK is 160 U/L. These results are consistent with Skeletal muscle injury. AMI. Unstable angina. A patient with normal values for both tests.

Skeletal muscle injury.

A urine sample submitted for a drug abuse screen is suspected of having been diluted with tap water. Which test would be most useful to evaluate the acceptability of the sample? Specific gravity Inorganic phosphorus Calcium pH

Specific gravity

A shift in the O2-Hgb dissociation curve to the right indicates that Buffering capacity of the hemoglobin is reduced. The affinity of hemoglobin for oxygen is lowered. The p50 value is lowered. Oxygen is less easily released in the tissues.

The affinity of hemoglobin for oxygen is lowered.

Which of the following cardiac markers would you expect to be increased 4 days after a myocardial infarction? Myoglobin CK-MB TNI CK-MB and myoglobin

TNI

A lipid profile performed on a serum sample from a patient known to have familial peripheral lipase deficiency gave the following results: Triglyceride = 860 mg/dL Total cholesterol = 230 mg/dL High-density lipoprotein (HDL) cholesterol = 110 mg/dL Which situation is most likely the cause of these results? The patient has a type II hyperlipoproteinemia. The triglyceride result is falsely elevated. The HDL cholesterol result is falsely elevated. The patient was not fasting 12 to 14 hours before sample collection.

The HDL cholesterol result is falsely elevated.

Which statement about TNI is true? The assay detects only TNI from cardiac muscle. Levels do not become abnormal until 12 hours after a myocardial infarction. Levels return to normal within 36 hours after a myocardial infarction. It can be measured by determining either mass units or by measurement of catalytic activity.

The assay detects only TNI from cardiac muscle.

A plasma cortisol at 8 a.m. is 25 µg/dL (reference range 5 to 20 µg/dL). A sample collected 12 hours later gives a result of 23 µg/dL (reference range 3 to 10 µg/dL). These results indicate The patient has Cushing syndrome. One of the specimens is invalid because there is no diurnal variation. Heterophile antibodies are present and are interfering with the immunoassay. The hook effect has occurred because of antigen excess.

The patient has Cushing syndrome.

An arterial blood gas sample collected from a patient under anaerobic conditions gave the following results: pH = 7.350 PCO2 = 28 mm Hg PO2 = 125 mm Hg These results most likely indicate that The patient's pH and gas exchange are normal. The sample is most likely venous blood. The patient was breathing more than 21% oxygen. An error was made in calibrating the blood gas analyzer.

The patient was breathing more than 21% oxygen.

For a drug that is administered by constant intravenous infusion The ratio of free to bound drug will be greater than that for oral administration of the drug. The peak trough difference will be zero. The drug will be subject to greater removal from first-pass hepatic metabolism than for other routes of administration. It will take longer to reach steady state than for oral administration.

The peak trough difference will be zero.

A spectrophotometer is known to be linear to an absorbance of 2.0. A sample is assayed, which produces an absorbance of 2.60. What should be done? The sample should be diluted 1:4 and reassayed. The concentration should be calculated using the Beer's Law formula. A standard of higher concentration should be compared to the sample. The sample should be assayed by the reference method.

The sample should be diluted 1:4 and reassayed.

The precursor from which the thyroid hormones are produced is Cholesterol. Dopamine. Methionine. Tyrosine.

Tyrosine.

Which enzyme is responsible for the conjugation of bilirubin? UDP glucuronyltransferase Heme oxygenase Bilirubin reductase β-Glucuronidase

UDP glucuronyltransferase

Given: pH = 7.22, PCO2 = 60 mm Hg, and bicarbonate = 24 mmol/L. These results are consistent with Compensated metabolic acidosis. Partly compensated respiratory alkalosis. Uncompensated respiratory acidosis. Partly compensated metabolic acidosis.

Uncompensated respiratory acidosis.

In hemolytic anemia, which bilirubin fraction is elevated? Conjugated Delta bilirubin Direct reacting Unconjugated

Unconjugated

A patient has the following plasma results: K = 6.2 mmol/L Chloride = 101 mmol/L Creatinine = 3.1 mg/dL BUN = 40 mg/dL Which test is most likely to be abnormally elevated? Calcium LD Sodium Uric acid

Uric acid

Which is the most appropriate specimen for performing a lead assay? Whole blood collected in sodium citrate with a light blue cap Plasma collected with EDTA in a tube with a navy-blue cap Whole blood collected with EDTA in a tube with a tan cap Serum collected in a sterile tube with a red cap-no additive

Whole blood collected with EDTA in a tube with a tan cap

Why must specimens for the measurement of ionized calcium be stored anaerobically? pH changes affect the protein binding of calcium. Atmospheric oxygen interferes with the ionized calcium electrode. The standards and controls are stored anaerobically. Loss of volatile calcium compounds can occur.

pH changes affect the protein binding of calcium.

A blood gas sample is brought to the laboratory capped but is not measured for 40 min. Which abnormal result would you expect? pH ↑, Pco₂ ↑, Po₂ ↓ pH ↓, Pco₂ ↑, Po₂ ↓ pH ↓, Pco₂ ↑, Po₂ ↑ pH ↑, Pco₂ ↓, Po₂ ↓

pH ↓, Pco₂ ↑, Po₂ ↓

Which analyte is increased in hepatic coma? Ammonia BUN Creatinine Uric acid

Ammonia

5-Hydroxyindoleacetic acid (5-HIAA) is a metabolic marker for CAH. Neuroblastoma. Monoamine oxidase deficiency. Carcinoid tumors of the intestine.

Carcinoid tumors of the intestine.

What is the purpose of cholesterol ester hydrolase in the cholesterol oxidase method? Converts esterified cholesterol to free cholesterol Oxidizes the cyclopentanoperhydrophenanthrene ring Separates the cholesterol from apoproteins Hydrolyzes the phospholipids and vitamins in the sample

Converts esterified cholesterol to free cholesterol