Creatinine (CREA), Urine

CPT Code: 82570
Specimen: Urine
Volume: 10 mL aliquot
Minimum Volume:

Random:  1 mL

24-hour:   0.5 mL aliquot

Container:

Plastic urine container, with or without 6N HCl

Methodology:

Kinetic

Collection:

If the specimen is a 24-hour collection instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Transport the specimen promptly to the laboratory. Container must be labeled with patient's full name, date and time collection started, and date and time collection finished.

Reference Range:  
Storage:

Store at 2-8 ⁰C

Stability

Temperatures Period 
Refrigerated (2-8 ⁰C) 4 Days

 

       

Use: Renal function test when used as part of creatinine clearance; crude marker for completeness of 24-hour urine collections when collected for other purposes.
Clinical Significance:

High creatinine especially with an elevated BUN, usually indicate kidney disease. It may also indicate insufficiency with decreased glomerular filtration, urinary tract obstruction, reduced renal blood flow including congestive heart failure, shock, dehydration, or rhabdomyolysis.

Low creatinine can be a cause of small stature, debilitation, or decreased muscle mass; some complex cases of severe hepatic disease can cause low serum creatinine levels. In advanced liver disease, low creatinine may result from decreased hepatic production of creatinine and inadequate dietary protein as well as reduced muscle mass

Limitations: Complete urine collections require vigilance on the part of nursing personnel. Ingestion of meat may increase creatinine values of urine collections as well as serum creatinine values. Drugs interfering with tubular creatinine secretion include cimetidine, trimethoprim, and probenecid. Creatinine reabsorption occurs with very low urine flow rates. Entities in which reabsorption occurs include severe congestive heart failure, uncontrolled diabetes mellitus, and acute renal failure.
Causes for Rejection: Times not indicated; improper labeling
Interfering Substances: Bilirium (unconjugated) at 20 mg/dL and 40 mg/dL decreases a CREA result of 1.7 mg/dL by 12% at standard sample volume.
 
Bilirium (conjugated) at 60 mg/dL decreases a CREA results of 1.7 mg/dL by 57% at standard sample volume.
 
Lipemia interference testing at levels 600 mg/dL, the magnitude of interference could not be determined.