Creatinine, 24 Hour, Urine

Casandra

Casandra Test Code MC46330Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID CTUCPT Code 82570

Creatinine, 24 Hour, Urine

Clinical Use

Use

Calculation of creatinine clearance, a measure of renal function, when used in conjunction with serum creatinine. Creatinine is produced mainly by muscle metabolism, minimally affected day-to-day, freely filtered by the glomeruli, and partly secreted by renal tubules; renal clearance of creatinine estimates glomerular filtration rate. Reference values (mg per 24 hours) are provided for males ≥18 years (930–2955 mg/24 hours) and females ≥18 years (603–1783 mg/24 hours); not established for patients under 18 years.

Special Instructions

24‑Hour volume (in milliliters) is required. Supplies: Sarstedt 5 mL Aliquot Tube (T914). Collection container: 24‑hour graduated urine container with no metal cap or glued insert. Submission container: plastic tube or clean plastic aliquot container with no metal cap or glued insert. Special instructions: see Renal Diagnostics Test Request (T830) form and Urine Preservatives‑Collection and Transportation for 24‑Hour Urine Specimens. Forms: Renal Diagnostics Test Request (T830) if not ordering electronically.

Limitations

Accuracy depends on correctly collected 24‑hour specimen. Intra‑individual variability may occur from differences in muscle mass or dietary protein intake. Acute changes in filtration prior to steady state can alter urinary creatinine excretion. Dietary intake of cooked meat may contribute to urinary creatinine levels.

Test Details

FDA Approved