Serum or Plasma Creatinine Concentration (Standard Method)

Why This Test Matters

Your kidneys filter waste products, including creatinine, from your blood. High levels of creatinine can indicate reduced kidney function or kidney disease, while low levels might suggest dehydration or overhydration. This test is often used alongside other kidney function tests to monitor overall kidney health, especially in people with risk factors like diabetes, high blood pressure, or a family history of kidney disease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. Stay hydrated unless your doctor advises otherwise. If you’re on a low-protein diet or taking certain medications, discuss this with your provider before testing.

Common Causes of Abnormal Results

Elevated creatinine levels may signal kidney issues, such as chronic kidney disease, acute kidney injury, or conditions that reduce blood flow to the kidneys (e.g., severe dehydration, heart failure). Other causes include muscle disorders, certain medications, or high blood pressure. Low levels might be due to overhydration, muscle wasting, or liver disease.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab, where it’s analyzed using a standard method to measure creatinine concentration. The result is typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).