Creatinine, 24-Hour Urine
Also known as: Urine Creatinine, 24-Hour
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.
Methodology
Automated Analyzer (Unknown)
Biomarkers
LOINC Codes
- 2162-6
- 2161-8
- 2162-6
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
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.
Storage Instructions
Room temperature
Causes for Rejection
Times not indicated; improper labeling
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 14 days |