Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 41

The largest source of error in creatinine clearance tests is:

A. Secretion of creatinine

B. Improperly timed urine specimens

C. Refrigeration of the urine

D. Time of collecting blood sample

Step 1 of 2

Clearance test:

The filtering ability of the glomeruli is measured using the standard tests which are called clearance test.

• It measures the ability of kidney to clear the filterable elements from the blood.

Types of clearance test:

• Creatinine

• Beta two-microglobuline

• Cystatin C

Creatinine clearance test:

• Creatinine is produced by creatine by the enzyme creatinine phosphokinase as a waste product of muscle metabolism.

• This creatinine is used to measure the filtering ability of glomeruli in the laboratory.

Errors in creatinine clearance test:

• The use of improperly timed urine specimens will be the largest error in the clearance procedure.

• Timed specimen or 24 hour urine specimen is obtained with an empty bladder for 24 hours exactly (Example: 7 Am to next day 7 Am).

Therefore, “improperly timed urine specimens” is the largest source of error in creatinine clearance test. Hence, the correct answer is option.