Total Serum Creatinine (with optional 24-hour urine collection for creatinine clearance calculation)

Why Your Kidneys Matter

Your kidneys are vital organs that filter waste and excess substances from your blood, including creatinine. This test helps doctors determine how well your kidneys are working by measuring the level of creatinine in your blood. Healthy kidneys remove creatinine efficiently, so higher levels may signal impaired kidney function.

What to Expect Before the Test

No special preparation is needed for a standard serum creatinine test. If your doctor orders a 24-hour urine creatinine test (often combined with creatinine clearance), you’ll need to collect all urine over 24 hours in a special container. For whole blood tests, you’ll have a small needle inserted into your arm.

What the Results Mean

Results alone don’t diagnose kidney disease—they’re part of a larger picture. Your doctor will compare your creatinine level to your age, sex, height, and other health factors. Higher levels may indicate reduced kidney function, while lower levels could suggest muscle loss or other conditions.

Common Causes of Abnormal Results

Elevated creatinine levels may be due to kidney disease, dehydration, severe muscle damage, or conditions that restrict blood flow to the kidneys. Lower levels might result from malnutrition, muscle atrophy, or certain medications. Always discuss your results with your healthcare provider.