Creatinine, 24-Hour Urine

Casandra

Casandra Test Code LC70484Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 003012CPT Code 82570

Creatinine, 24-Hour Urine

Also known as: Urine Creatinine, 24-Hour

Clinical Use

Order Test

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

Special Instructions

It is crucial to record the total 24-hour urine volume on the request form. The test is not ordered independently but typically accompanies a serum creatinine assessment for accurate renal function data. Accurate 24-hour urine collection requires diligent tracking by nursing personnel.

Limitations

Incomplete urine collections can arise from lapses in collection protocol. Consuming meat may falsely elevate both urine and serum creatinine levels. Several drugs, such as cimetidine, trimethoprim, and probenecid, might interfere with creatinine secretion. In conditions where urine flow is extremely low, such as severe congestive heart failure, uncontrolled diabetes mellitus, and acute renal failure, there might be reabsorption of creatinine, affecting test accuracy.

Test Details

Methodology

Automated Analyzer (Unknown)

Biomarkers

Creatinine, Urine

Analyte

Creatinine, Urine • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Creatinine, Urine 24hr

Analyte

Creatinine, Urine 24hr • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

2162-6

Result Codes

2161-8
2162-6

Result Turnaround Time

1 day

Specimen

Urine

Volume

10 mL aliquot of entire collection

Minimum Volume

0.5 mL aliquot

Container

Plastic urine container, with or without 6N HCl

Collection Instructions

If the specimen is a 24-hour collection, instruct the patient to void at 8 AM and discard that sample. Then collect all urine, including the final specimen voided at the end of the 24-hour collection period (i.e., 8 AM the next morning). Screw the lid on securely and promptly transport to the laboratory. Label with the patient's full name, and the start and end dates and times of the collection.