Serum or Plasma Creatinine Concentration (Substance Concentration)

Why This Test Matters

Creatinine is a byproduct of muscle breakdown and is normally filtered out of your blood by your kidneys. If your kidneys aren’t working well, creatinine levels can build up in your blood. This test helps doctors monitor kidney health, especially in people with diabetes, high blood pressure, or other conditions that may affect the kidneys.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, but this depends on your doctor’s instructions. Blood is drawn from a vein, usually in your arm. It’s quick and usually doesn’t cause discomfort. If you’re on certain medications or have a history of bleeding disorders, let your doctor know before the test.

How the Test Works

The test uses a blood sample to measure creatinine levels. The method may involve enzymatic or chemiluminescent techniques to detect and quantify the waste product. Your results will be compared to a reference range to determine if your kidneys are functioning normally.

Common Reasons for This Test

Doctors may order this test if you have symptoms like fatigue, swelling, or frequent urination, or if you have a condition that puts you at risk for kidney problems, such as diabetes or high blood pressure. It’s also used to monitor kidney function in people already on dialysis or with chronic kidney disease.