Serum or Plasma Creatinine Concentration (Mass Concentration)

Why This Test Matters

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

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other blood tests. If you’re on a low-protein diet or have recently exercised, your doctor may advise you to wait a few days before testing to get more accurate results.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While reference ranges vary by lab, higher than expected levels may signal kidney problems, while very low levels could indicate dehydration or other health concerns. Your doctor will interpret the results in the context of your overall health and medical history.

Common Causes of Abnormal Results

High creatinine levels can be caused by kidney disease, dehydration, severe muscle injury, or conditions that reduce blood flow to the kidneys. Low levels may occur due to dehydration, overhydration, or certain medications. Other factors, like age, sex, and muscle mass, can also influence results.