Serum Creatinine (with or without 24-hour urine collection for creatinine clearance)

Why This Test Matters

Creatinine is a waste product made by muscles during normal metabolism. Healthy kidneys filter it from your blood and remove it from your body through urine. If your kidneys aren’t working well, creatinine levels in your blood can rise, which may indicate kidney problems. This test is often used to monitor kidney function, especially if you have conditions like diabetes, high blood pressure, or a history of kidney issues.

What to Expect Before the Test

You’ll typically have a small needle inserted into your arm to draw blood. If your doctor orders a 24-hour urine test for creatinine clearance, you’ll need to collect all urine for a full day (starting after the first morning void). Follow your doctor’s instructions carefully to ensure accurate results.

What the Results Mean

Results are compared to a general reference range for healthy adults, though individual ranges can vary by lab. High levels may signal kidney problems, while very low levels (rare) could indicate muscle disorders or overhydration. Your doctor will interpret results in the context of your overall health.

Common Conditions Monitored

This test is commonly used to monitor kidney function in conditions like chronic kidney disease, diabetes, high blood pressure, and after treatments for conditions that may affect the kidneys (e.g., chemotherapy). It’s also part of routine check-ups for people at higher risk of kidney issues.