Serum or Plasma Creatinine Concentration (Standard Method)

Why This Test Matters

Creatinine is a byproduct of muscle breakdown and is filtered out of your blood by your kidneys. High levels can indicate poor kidney function, while low levels may suggest overhydration or other conditions. This test is often used alongside other kidney function tests to monitor kidney health, especially in people with diabetes, high blood pressure, or a history of kidney disease.

What to Expect Before the Test

You may be asked to fast for 8–12 hours before the test, but this is not always required. Your blood will be drawn from a vein, usually in your arm. If you’re on dialysis, your test may be collected from your dialysis access site. Avoid strenuous activity or heavy meals 24 hours before testing to ensure accurate results.

How the Test Works

Your blood sample is sent to a lab where it is analyzed using a standard method, often involving enzymatic or colorimetric techniques. The lab measures the concentration of creatinine in your serum or plasma to determine its level.

Common Causes of Abnormal Results

High creatinine levels may signal kidney problems, dehydration, or muscle disorders. Low levels could indicate overhydration, liver disease, or certain medications. Always discuss your results with your healthcare provider, as they’ll consider your overall health and other tests.