Renal function: Creatinine Clearance (24-hour urine collection)

Why This Test Is Done

Your doctor may order this test if they suspect kidney disease, need to monitor kidney function before or after treatment, or evaluate kidney function in people with conditions like diabetes or high blood pressure. It’s also used to check kidney function in people with chronic kidney disease or after kidney surgery.

What to Expect Before the Test

You’ll need to collect all your urine for a full 24-hour period, typically starting after midnight one day and ending the same time the next day. Drink plenty of fluids to help your kidneys produce enough urine, but avoid excessive caffeine or diuretics unless instructed otherwise. Your doctor or lab technician will provide detailed instructions to ensure accurate results.

During the Test

You’ll collect your urine in a special container at home or at a clinic, depending on your doctor’s instructions. You’ll need to empty your bladder completely at the start and end of the 24-hour period, discarding those samples. Your collected urine will be sent to a lab for analysis.

What Happens After the Test

After completing the urine collection, your lab results will be analyzed to calculate your creatinine clearance rate. This rate helps determine how efficiently your kidneys are filtering waste from your blood. Your doctor will review the results with you to discuss any findings or next steps.