Serum Creatinine Concentration

Why This Test Matters

Creatinine is a byproduct of muscle breakdown and is normally filtered out by your kidneys. High levels in the blood can indicate kidney damage or reduced kidney function, even if other tests show no signs of kidney disease. This test is often used alongside other blood tests to monitor kidney health, especially in people with diabetes, high blood pressure, or a family history of kidney problems.

What to Expect Before the Test

You won’t need to prepare for this test. It’s typically done by having a small blood sample drawn from your arm. If you’re on a dialysis regimen, your doctor may adjust timing to avoid interference. Avoiding certain medications (like NSAIDs) for a few days before testing may be advised by your healthcare provider, but always confirm with them.

How the Test Works

Your blood sample is sent to a lab where it’s analyzed to measure creatinine levels. The test uses a method called **nephelometry** (a type of nephelometric assay) to detect and quantify creatinine in your serum. Results are compared to reference ranges to determine if your kidneys are functioning normally.

Common Reasons for Testing

Doctors order creatinine tests to monitor kidney function, diagnose kidney disease, evaluate symptoms like swelling, fatigue, or changes in urine, or check for complications in conditions like diabetes or heart disease. It’s also used before surgeries or procedures to assess kidney health.