Creatinine, 24-Hour Urine

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

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.¹

Urine creatinine is not ordered alone. Creatinine clearance, which requires a serum creatinine, offers useful renal function data. Serum creatinine alone is not an adequate index of glomerular filtration rate.¹

1. Levey AS, Perrone RD, Madias NE. Serum creatinine and renal function. Annu Rev Med. 1988; 39:465-490 (review). PubMed 3285786