Chemistry 6.4 Creatinine, Uric Acid, BUN, and Ammonia Flashcards
Creatinine is formed from the:
A. Oxidation of creatine
B. Oxidation of protein
C. Deamination of dibasic amino acids
D. Metabolism of purines
A. Oxidation of creatine
Creatinine is considered one of the substances of choice to measure endogenous renal clearance because:
A. The rate of formation per day is independent of body size
B. It is completely filtered by the glomeruli
C. Plasma levels are highly dependent upon diet
D. Clearance is the same for both men and women
B. It is completely filtered by the glomeruli
Which statement regarding creatinine is true?
A. Serum levels are elevated in early renal disease
B. High serum levels result from reduced glomerular filtration
C. Serum creatine has the same diagnostic utility as serum creatinine
D. Serum creatinine is a more sensitive measure of renal function than creatinine clearance
B. High serum levels result from reduced glomerular filtration
Which of the following formulas is the correct expression for creatinine clearance?
A. Creatinine clearance = U/P × V × 1.73/A
B. Creatinine clearance = P/V × U × A/1.73
C. Creatinine clearance = P/V × U × 1.73/A
D. Creatinine clearance = U/V × P × 1.73/A
A. Creatinine clearance = U/P × V × 1.73/A
Which of the following conditions is most likely to cause a falsely high creatinine clearance result?
A. The patient uses the midstream voiding procedure when collecting his or her urine
B. The patient adds tap water to the urine container because he or she forgets to save one of the urine samples
C. The patient does not empty his or her bladder at the conclusion of the test
D. The patient empties his or her bladder at the start of the test and adds the urine to the collection
D. The patient empties his or her bladder at the start of the test and adds the urine to the collection
The modification of diet in renal disease (MDRD) formula for calculating estimated glomerular filtration rate (eGFR) requires which four parameters?
A. Urine creatinine, serum creatinine, height, weight
B. Serum creatinine, age, gender, race
C. Serum creatinine, height, weight, age
D. Urine creatinine, gender, weight, age
B. Serum creatinine, age, gender, race
What substance may be measured as an alternative to creatinine for evaluating GFR?
A. Plasma urea
B. Cystatin C
C. Uric acid
D. Potassium
B. Cystatin C
Which of the following enzymes allows creatinine to be measured by coupling to a peroxidase reaction?
A. Glucose-6-phosphate dehydrogenase
B. Creatinine deaminase
C. Sarcosine oxidase
D. Creatine kinase (CK)
C. Sarcosine oxidase
Select the primary reagent used in the Jaffe method for creatinine.
A. Alkaline copper II sulfate
B. Saturated picric acid and sodium hydroxide (NaOH)
C. Sodium nitroprusside and phenol
D. Phosphotungstic acid
B. Saturated picric acid and sodium hydroxide (NaOH)
Interference from other reducing substances can be partially eliminated in the Jaffe reaction by:
A. Measuring the product at 340 nm
B. Measuring the product with an electrode
C. Measuring the timed rate of product formation
D. Performing a sample blank
C. Measuring the timed rate of product formation
Which of the following statements is true?
A. Cystatin C is measured immunochemically
B. The calibrator used for cystatin C is traceable to the National Bureau of Standards calibrator
C. Cystatin C assays have a lower coefficient of variation compared with plasma creatinine
D. Enzymatic and rate Jaffe reactions for creatinine give comparable results
A. Cystatin C is measured immunochemically
In which case would eGFR derived from the plasma creatinine likely give a more accurate measurement of GFR compared with measurement of plasma cystatin C?
A. Diabetes
B. Chronic renal failure
C. After renal transplantation
D. Chronic hepatitis
C. After renal transplantation
A sample of amniotic fluid collected for fetal lung maturity studies from a woman whose pregnancy was compromised by hemolytic disease of the fetus and newborn (HDFN) has a creatinine level of 88 mg/dL. What is the most likely cause of this result?
A. The specimen is contaminated by blood
B. Bilirubin has interfered with the measurement of creatinine
C. A random error occurred when the absorbance signal was being processed by the analyzer
D. The fluid is urine from accidental puncture of the urinary bladder
D. The fluid is urine from accidental puncture of the urinary bladder
Which analyte should be reported as a ratio using creatinine concentration as a reference?
A. Urinary microalbumin
B. Urinary estriol
C. Urinary sodium
D. Urinary urea
A. Urinary microalbumin
Urea is produced from:
A. The catabolism of proteins and amino acids
B. Oxidation of purines
C. Oxidation of pyrimidines
D. The breakdown of complex carbohydrates
A. The catabolism of proteins and amino acids