OAE - Clinical Chemistry Part 4

D. Urea

What is the compound that comprises the majority of the nonprotein-nitrogen fractions in serum?

a. Uric acid

b. Creatinine

c. Ammonia

d. Urea

B. 2.14

Urea concentration is calculated from the BUN by multiplying by a factor of:

a. 0.5

b. 2.14

c. 6.45

d. 14

D. 64 mg/dL

Express 30 mg/dL of urea nitrogen as urea

a. 14 mg/dL

b. 20 mg/dL

c. 50 mg/dL

d. 64 mg/dL

B. Sodium fluoride

In the urea method, the enzymatic action of urease is inhibited when blood for analysis is drawn in a tube containing what anticoagulant?

a. Sodium heparin

b. Sodium fluoride

c. Sodium oxalate

d. EDTA

B. Urea

In the diacetyl method, what does diacetyl react with to form a yellow product?

a. Ammonia

b. Urea

c. Nitric acid

d. Nitrogen

D. Diabetes mellitus

Which of the following disorders is not associated with an elevated blood ammonia level?

a. Reye syndrome

b. Renal failure

c. Chronic liver failure

d. Diabetes mellitus

A. The patient had two cigarettes 15 minutes prior to blood draw

When measuring ammonia blood levels, which of the following might cause a false increase in this analyte?

a. The patient had two cigarettes 15 minutes prior to blood draw

b. The patient was fasting for hours prior to blood collection

c. Immediately after phlebotomy, the blood sample was maintained on ice'

d. The patient had a steak dinner the night before the blood draw

e. None of the above will falsely increase the blood ammonia levels.

A. Glomerular filtration rate is decreased by at least 50%

The assay for urea is only a rough estimate of renal function and will not show any significant level increased concentration until the glomerular filtration rate is decreased by at least ___.

a. Glomerular filtration rate is decreased by at least 50%

b. Glomerular filtration rate is decreased by at least 60%

c. Glomerular filtration rate is decreased by at least 70%

d. Glomerular filtration rate is decreased by at least 80%

D. Creatinine

What compound normally found in urine may be used to assess the completeness of a 24-hour urine collection?

a. Urea

b. Uric acid

c. Creatine

d. Creatinine

D. Uric acid

When mixed with phosphotungstic acid, what compound causes the reduction of the former to a tungsten blue complex?

a. Urea

b. Ammonia

c. Creatinine

d. Uric acid

A. Chronic renal failure

Which of the following disorders is best characterized by laboratory findings that include increased serum levels of inorganic phosphorus, magnesium, potassium, uric acid, urea, and creatinine, and decreased serum calcium and erythropoietin levels?

a. Chronic renal failure

b. Renal tubular disease

c. Nephrotic syndrom

d. Acute glomerulonephritis

D. Uric Acid

In gout, what analyte deposits in joints and other body tissues?

a. Calcium

b. Creatinine

c. Urea

d. Uric acid

A. Lesch-Nyhan syndrome

A complete deficiency of hypoxanthine guanine phosphoribosyltransferase results in which disease?

a. Lesch-Nyhan syndrome

b. Maple syrup urine disease

c. Reye's syndrome

d. Megaloblastic anemia

A. Uric acid

During chemotherapy for leukemia, which of the following analytes would most likely be elevated in the blood?

a. Uric acid

b. Urea

c. Creatinine

d. Ammonia

D. Biliverdin

What is the immediate precursor of bilirubin formation?

a. Mesobilirubinogen

b. Verdohemoglobin

c. Urobilinogen

d. Biliverdin

B. Azobilirubin

To quantify serum bilirubin levels, it is necessary that bilirubin couples with diazotized sulfanilic acid to form what complex?

a. Verdobilirubin

b. Azobilirubin

c. Azobilirubinogen

d. Bilirubin glucorinide

C. Uridine diphosphate glucoronyltransferase

What enzyme catalyzes the conjugation of bilirubin?

a. Leucine aminopeptidase

b. Glucose-6-phosphate dehydrogenase

c. Uridine diphosphate glucoronyltransferase

d. Carbamoyl phosphate synthase

B. Urobilin

What breakdown product of bilirubin metabolism is produced in the colon from the oxidation of urobilinogen by microorganisms?

a. Porphobilinogen

b. Urobilin

c. Stercobilinogen

d. Protoporphyrin

A. Albumin

Which of the following functions as a transport protein for bilirubin in the blood?

a. Albumin

b. Alpha-globulin

c. Beta-globulin

d. Gamma-globulin

A. Jaundice

What term is used to describe the accumulation of bilirubin in the skin?

a. Jaundice

b. Hemolysis

c. Cholestasis

d. Kernicterus

A. Brain

In the condition kernicterus, the abnormal accumulation of bilirubin occurs in what tissue?

a. Brain

b. Liver

c. Kidney

d. Blood

B. Urobilinogen

As a reduction product of bilirubin catabolism, this compound is partially reabsorbed from the intestine through the portal circulation for reexcretion by the liver. What is this compound?

a. Verdohemoglobin

b. Urobilinogen

c. Urobilin

d. Biliverdin

D. Specimen Refrigeration

Which of the following factors will not adversely affect the accurate quantification of bilirubin in serum?

a. Lipemia

b. Hemolysis

c. Exposure to light

d. Specimen refrigeration

C. Delta

Which bilirubin fraction is conjugated and covalently bound to albumin?

a. Alpha

b. Beta

c. Delta

d. Gamma

A. Spleen

As the red blood cells disintegrate, hemoglobin is released and converted to the pigment bilirubin. Which organ is primarily responsible for this function?

a. Spleen

b. Kidnyes

c. Intestines

d. Liver

A. Insoluble in water

Which of the following does not accurately describe direct bilirubin?

a. Insoluble in water

b. Conjugated in the liver

c. Conjugated with glucuronic acid

d. Excreted in the urine of jaundiced patients

A. Conjugated bilirubin

Excreted in the urine of jaundiced patients:

a. Conjugated bilirubin

b. Unconjugated bilirubin

c. Both of these

d. None of these

C. Diazo

Which of the following reagent systems contains the components sulfanilic acid, hydrochloric acid, and sodium nitrite?

a. Jaffe

b. Zimmerman

c. Diazo

d. Lowry

Caffeine-sodium benzoate

Indirect-reacting bilirubin may be quantified by reacting it initially in which reagent?

a. Dilute hydrochloric acid

b. Dilute sulfuric acid

c. Caffeine-sodium benzoate

d. Sodium hydroxide

D. Obstructive Jaundice

What condition is characterized by an elevation of total bilirubin primarily due to an increase in the conjugated bilirubin fraction?

a. Hemolytic jaundice

b. Neonatal jaundice

c. Criggler-Najjar syndrome

d. Obstructive Jaundice

A. Unconjugated serum bilirubin level increased

Which of the following is characteristic of hemolytic jaundice?

a. Unconjugated serum bilirubin level increased

b. Urinary bilirubin level increased

c. Urinary urobilinogen level decreased

d. Fecal urobilin level decreased

D. Deficiency in the bilirubin conjugation enzyme system

What may be the cause of neonatal physiological jaundice?

a. Hemolytic episode caused by an ABO incompatibility

b. Structure of the common bile duct

c. Hemolytic episode caused by an Rh incompatibility

d. Deficiency in the bilirubin conjugation enzyme system

D. Gilbert syndrome

Which of the following disorders is characterized by an inability to transport bilirubin from the sinusoidal membrane into the hepatocyte?

a. Carcinoma of the common bile duct

b. Crigler-Najjar syndrome

c. Dubin-Johnson syndrome

d. Gilbert syndrome

B. Deficiency of the enzyme system required for conjugation of bilirubin

Which of the following characterizes Crigler-Najjar syndrome?

a. Inability to transport bilirubin from the sinusoidal membrane to the microsomal region

b. Deficiency of the enzyme system required for conjugation of bilirubin

c. Inability to transport bilirubin glucoronides to the bile cannaliculi

d. Severe liver cell damage accompanied by necrosis

C. Inability to conjugate bilirubin

Which of the following is not characteristic of Dubin-Johnson syndrome?

a. Impaired excretion of bilirubin into the bile

b. Hepatic uptake of bilirubin is normal

c. Inability to conjugate bilirubin

d. Increased level of bilirubin in urine

B. Hepatic cirrhosis

Beta-gamma bridging effect:

a. Multiple myeloma

b. Hepatic cirrhosis

c. Nephrotic syndrome

d. Inflammation

A. Hepatitis

Less than 80% liver damageL

a. Hepatitis

b. Cirrhosis

B. Cirrhosis

80% liver tissue damage:

a. Hepatitis

b. Cirrhosis

A. Cirrhosis

Destruction of liver architecture:

a. Cirrhosis

b. Hepatitis

c. Bile duct obstruction

d. None of these

C. B1 and B2

Increased in hepatic jaundice

a. B1 only

b. B2 only

c. B1 and B2

d. None of these

C. Tissue damage and necrosis

What does an increase in the serum enzyme levels indicate?

a. Decreased enzyme catabolism

b. Accelerated enzyme production

c. Tissue damage and necrosis

d. Increased glomerular filtration rate

A. Lower than expected

When measuring enzyme activity, if the instrument is operating 5C lower than the temperature prescribed for the method, how will the results be affecte?

a. Lower than expected

b. Higher than expected

c. Varied, showing no particular pattern

d. All will be clinically abnormal

B. Enzymes are protein catalysts of biological origin

The properties of enzymes are correctly described by which of the following statements?

a. Enzymes are stable proteins

b. Enzymes are protein catalysts of biological origin

c. Enzymes affect the rate of a chemical reaction by raising the activation energy needed for the reaction to take place

C. Lock-and-key theory by Emil Fischer

The shape of the key (substrate) must fit into the lock (enzyme):

a. Induced-fit theory by Emil Fischer

b. Induced-fit theory by Daniel Koshland

c. Lock-and-key theory by Emil Fischer

d. Lock-and-key theory by Daniel Koshland

A. First order kinetics

The reaction rate is directly proportional to substrate concentration:

a. First order kinetics

b. Zero order kinetics

B. Zero-order kinetics

The reaction rate depends only on enzyme concentration:

a. First-order kinetics

b. Zero-order kinetics

B. Kinetic Assay

Multiple measurements, usually of absorbance change, are made during the reaction, either at specific time intervals (usually every 30 or 60 seconds) or continuously by a continuous-recording spectrophotometer:

a. Fixed time assay

b. Kinetic assay

B. Coenzyme

An organic cofactor, such as nicotinamide adenine dinucleotide (NAD):

a. Activator

b. Coenzyme

c. Proenzyme

d. Zymogen

A. Activator

Inorganic cofactors such as chloride or magnesium ions:

a. Activator

b. Coenzyme

c. Proenzyme

d. Zymogen

D. Transferases

Enzymes that catalyze the transfer of groups between compounds are classified as belonging to which enzyme class?

a. Hydrolases

b. Lyases

c. Oxidoreductases

d. Transferases

B. Aldolase

Which of the following enzymes does not belong to the class of enzymes known as the hydrolases?

a. Alkaline phosphatase

b. Aldolase

c. Amylase

d. Lipase

Answer: C. Oxidoreductases

To what class of enzymes does lactate dehydrogenase belong?

a. Isomerases

b. Ligases

c. Oxidoreductases

d. Transferases

D. Ligases

Catalyze the joining of two substrate molecules, coupled ith breaking of the pyrophosphate bond in adenosine triphosphate (ATP) or a similar compound:

a. Oxidoreductases

b. Hydrolases

c. Lyases

d. Ligases

A. Decreasing the activation energy

Enzymes catalyze physiologic reactions by ___ the activation energy level that the reactants (substrates) must reach for the reaction to occur.

a. Decreasing the activation energy

b. Increasing the activation energy

B. Pernicious anemia and hemolytic disorders

The highest levels of total LD are seen in

a. AMI and pulmonary infraction

b. Pernicious anemia and hemolytic disorders

c. Skeletal muscle disorders

d. Viral hepatitis and cirrhosis

D. LD-5

Most labile LD isoenzyme:

a. LD1

b. LD2

c. LD3

d. LD4

e. LD5

D. Paget's disease

The highest elevations of ALP activity occur in:

a. Biliary tract obstruction

b. Hepatitis

c. Osteomalacia

d. Paget's disease

D. Bone Disease

Which of the following disorders is not associated with an elevation of serum creatine kinase?

a. Duchenne-type progressive muscular dystrophy

b. Myocardial infarction

c. Cerebrovascular accidents (stroke)

d. Bone disease

e. Intramuscular injection

A. Creatine kinase

To aid in the diagnosis of skeletal muscle disease, which of the following serum enzyme measurements would be of most use?

a. Creatine kinase

b. Alkaline phosphatase

c. Aspartate aminotransferase

d. Alanine aminotransferase

C. CK, AST, LD

When an AMI occurs, in what order (list first to last) will the enzymes aspartate aminotransferase (AST), creatine kinase (CK), and lactate dehydrogenase (LD) become elevated in the serum?

a. AST, LD, CK

b. CK, LD, AST

c. CK, AST, LD

d. LD, CK, AST

C. Cholinesterase

Pathological levels are decreased from the normal values, sometimes as much as 80 to 90%:

a. Acid phosphatase

b. Alkaline phosphatase

c. Cholinesterase

d Creatine kinase

A. Amylase

The smallest enzyme:

a. Amylase

b. Lipase

c. CK

d. GGT

E. G6PD

All of the following are macroenzymes except:

a. ACP and ALP

b. ALT and AST

c. CK

d. GGT

e. G6PD

A. p-Nitrophenyl phosphate

Which substrate is used in the Bowers-McComb method for ALP?

a. p-Nitrophenyl phosphate

b. B-Glycerophosphate

c. Phenylphosphate

d. a-Naphthylphosphate

C. 2-amino-2-methy-1-propanol

Which of the following buffers is used in the IFCC recommended method for ALP?

a. Glycine

b. Phosphate

c. 2-amino-2-methy-1-propanol

d. Citrate

A. Liner phase

Kinetic enzymatic assays are best performed during which phase of an enzymatic reaction?

a. Linear phase

b. Lag phase

c. Plateau phase

d. Any phase as long as temperature and pH are constant

B. Copper

To what metal does ceruloplasmin firmly bind?

a. Chromium

b. Copper

c. Zinc

d. Iron

A. Chromium

Which trace metal is contained in glucose tolerance factor?

a. Chromium

b. Copper

c. Selenium

d. Zinc

A. Parkinson's disease

Manganese toxicity resembles the following disease:

a. Parkinson's disease

b. Wilson's disease

c. Alzheimer's disease

d. Menke's disease

C. Molybdenum

The metal ion essential for the activity of xanthine oxidase and xanthin dehydrogenase is:

a. Iron

b. Manganese

c. Molybdenum

d. Zinc