nonprotein nitrogenous compounds

Question 1

What is the compound that comprises the
majority of the nonprotein-nitrogen
fractions in serum?
A. Uric acid
B. Creatinine
C. Ammonia
D. Urea

Answer 1

D

Question 2

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

Answer 2

D

Question 3

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. Ethylenediaminetetra-acetic acid

Answer 3

B

Question 4

In the diacetyl method, what does diacetyl
react with to form a yellow product?
A. Ammonia
B. Urea
C. Uric acid
D. Nitrogen

Answer 4

B

Question 5

What endogenous substance may cause a
positive interference in the urease/glutamate dehydrogenase assay?
A. Ammonia
B. Creatinine
C. Glucose
D. Cholesterol

Answer 5

A

Question 6

Which of the following methods utilizes
urease and glutamate dehydrogenase for
the quantification of serum urea?
A. Berthelot
B. Coupled enzymatic
C. Conductimetric
D. Indicator dye

Answer 6

B

Question 7

In the Berthelot reaction, what contaminant will cause the urea level to be falsely
elevated?
A. Sodium fluoride
B. Protein
C. Ammonia
D. Bacteria

Answer 7

C

Question 8

To maintain acid-base balance, it is
necessary that the blood ammonia level
be kept within narrow limits. This is
accomplished primarily by which of the
following?
A. Synthesis of urea from ammonia
B. Synthesis of glutamine from ammonia
C. Excretion of ammonia in the bile
D. Excretion of ammonia in the stools

Answer 8

A

Question 9

When a blood ammonia determination is
performed, the blood specimen must be
treated in a manner that will ensure that
A. The deamination process continues
in vitro
B. Glutamine formation in vitro is
avoided
C. The transamination process continues
in vitro
D. Ammonia formation in vitro is avoided

Answer 9

D

Question 10

. Which of the following does not need to
be done when collecting, handling, and
using a specimen for ammonia analysis?
A. Avoid using a hemolyzed specimen.
B. Collect blood in EDTA or heparin
evacuated tubes.
C. Place specimen in a 37°C water bath
immediately.
D. Advise patient not to smoke for
8 hours before blood collection.

Answer 10

C

Question 11

Which of the following statements can be
associated with the enzymatic assay of
ammonia?
A. Increase in absorbance monitored at
340 nm
B. Nicotinamide-adenine dinucleotide
(NAD+) required as a cofactor
C. Ammonium ion isolated from
specimen before the enzymatic step
D. Reaction catalyzed by glutamate
dehydrogenase

Answer 11

D

Question 12

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

Answer 12

D

Question 13

An increased serum level of which of the
following analytes is most commonly
associated with decreased glomerular
filtration?
A. Creatinine
B. Uric acid
C. Urea
D. Ammonia

Answer 13

A

Question 14

A serum creatinine was found to be
6.0 mg/dL. Which of the following urea
nitrogen serum results would support the
same pathological condition?
A. 6 mg/dL
B. 20 mg/dL
C. 35 mg/dL
D. 70 mg/dL

Answer 14

D

Question 15

From what precursor is creatinine formed?
A. Urea
B. Glucose
C. Creatine
D. Uric acid

Answer 15

C

Question 16

What analyte is measured using the Jaffe
reaction?
A. Urea
B. Uric acid
C. Ammonia
D. Creatinine

Answer 16

D

Question 17

When the Jaffe reaction is employed as a
kinetic assay to quantify serum creatinine,
which of the following is used in the
analysis?
A. Serum sample used directly
B. Folin-Wu filtrate
C. Somogyi-Nelson filtrate
D. Trichloroacetic acid filtrate

Answer 17

A

Question 18

The creatinine clearance test is routinely
used to assess the glomerular filtration
rate. Given the following information
for an average-size adult, calculate a
creatinine clearance.
Urine creatinine—120 mg/dL
Plasma creatinine—1.2 mg/dL
Urine volume for 24 hours—1520 mL
A. 11 mL/min
B. 63 mL/min
C. 95 mL/min
D. 106 mL/min

Answer 18

D

Question 19

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

Answer 19

D

Question 19

When it is not possible to perform a
creatinine assay on a fresh urine specimen,
to what pH level should the urine be
adjusted?
A. 3.0
B. 5.0
C. 7.0
D. 9.0

Answer 19

C

Question 20

Which of the following reagents is not
utilized in a coupled enzymatic reaction
method to quantify serum creatinine?
A. Picric acid
B. Chromogenic dye
C. Creatinine amidohydrolase
D. Sarcosine oxidase

Answer 20

A

Question 21

An endogenous substance assayed to
assess the glomerular filtration rate may
be described as being filtered by the
glomeruli, not reabsorbed by the tubules,
and only secreted by the tubules when
plasma levels become elevated. What is
this frequently assayed substance?
A. Inulin
B. Uric acid
C. Creatinine
D. Urea

Answer 21

C

Question 22

What is the end product of purine
catabolism in humans?
A. Urea
B. Uric acid
C. Allantoin
D. Ammonia

Answer 22

B

Question 23

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

Answer 23

D

Question 24

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 syndrome
D. Acute glomerulonephritis

Answer 24

A

Question 25

In gout, what analyte deposits in joints and
other body tissues?
A. Calcium
B. Creatinine
C. Urea
D. Uric acid

Answer 25

D

Question 26

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

Answer 26

A