Serum or Plasma Creatinine Concentration (Quantitative)

Why This Test Matters

Creatinine is a byproduct of muscle breakdown and is naturally filtered out of your blood by your kidneys. High levels can indicate poor kidney function, while low levels might suggest overhydration or other conditions. This test is a key part of routine health checks and monitoring for kidney disease.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood draw from a vein in your arm or, in some cases, a urine sample (though creatinine is typically measured in blood). If you’re on a low-protein diet or have had recent muscle activity, your doctor may advise timing your test accordingly.

How the Test Works

Blood is drawn and sent to a lab, where it is analyzed to measure creatinine concentration. The test uses a method like enzymatic or nephelometric techniques to detect and quantify this waste product. Plasma or serum (blood without clotting factors) is commonly used for this measurement.

Common Causes of Abnormal Results

High creatinine levels may signal kidney problems, dehydration, or conditions that increase muscle breakdown (e.g., severe illness or injury). Low levels could suggest overhydration, liver disease, or certain medications. Your doctor will consider your overall health and other test results to interpret results accurately.