Creatinine Clearance (from 24-hour urine collection)

Why This Test Is Done

Your doctor may order this test if they suspect kidney disease, monitor kidney function over time, or evaluate conditions that affect kidney blood flow, such as high blood pressure or diabetes. It’s also used before surgeries or procedures that could impact kidney function.

How the Test Works

You’ll collect all urine for a full 24-hour period in a special container. The test measures the amount of creatinine in your urine and compares it to a blood sample taken at the start of the collection period to calculate how well your kidneys are filtering waste.

What to Expect Before the Test

No special preparation is needed, but you should drink enough water to produce urine throughout the day. Avoid taking certain medications (like some pain relievers or diuretics) without talking to your doctor first, as they may affect results.

What to Expect During the Test

You’ll collect all urine in a container for 24 hours, changing the container every time you urinate. A small blood sample may be taken at the start to measure baseline creatinine levels. The test is simple but requires careful timing and consistency in urine collection.