Creatinine Clearance (Serum-Based, 24-Hour Urine Collection)

What Is Creatinine Clearance Used For?

Creatinine clearance is primarily used to evaluate kidney function by estimating how effectively your kidneys remove creatinine—a waste product from muscle metabolism—from your blood. It’s especially useful when other kidney function tests (like blood creatinine alone) may not provide enough information.

How Is This Test Performed?

To calculate creatinine clearance, you’ll typically provide a blood sample (serum) and a 24-hour urine collection. Blood is drawn once, while urine is collected over the full day. The lab compares the creatinine levels in your blood and urine to estimate how much blood your kidneys filter each minute.

Why Might Your Doctor Order This Test?

Your doctor may order creatinine clearance if they suspect kidney disease, monitor kidney function in chronic conditions (like diabetes or hypertension), or assess how well a kidney transplant or dialysis is working. It’s also used before surgeries or procedures that could affect kidney function.

What Do Results Mean?

Results are interpreted in relation to your age, sex, and body size. Lower than expected clearance may indicate kidney damage or disease, while higher values could suggest dehydration or overhydration. Your doctor will discuss the results in the context of your overall health.