Serum or Plasma Creatinine Concentration (Quantitative)

Why This Test Matters

Your kidneys filter waste products, including creatinine, from your blood. High levels of creatinine may indicate reduced kidney function or damage, while low levels could suggest overhydration or other conditions. This test is often used alongside other measures to monitor 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 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 instructed otherwise, as dehydration can affect results. Avoid strenuous activity the day before.

How the Test Is Performed

A healthcare provider will collect a blood sample from a vein in your arm using a small needle. The sample is then sent to a lab for analysis. If a urine sample is used, you’ll collect a small amount in a container at home or during a visit.

Possible Results and Interpretation

Results are typically reported in milligrams per deciliter (mg/dL) or micromoles per liter (µmol/L). While reference ranges vary by lab, higher-than-normal levels may signal kidney issues, while very low levels may warrant further investigation. Your doctor will interpret results in the context of your overall health.