Plasma or Serum Creatinine Concentration (Mass Concentration)

Why Your Kidneys Matter

Your kidneys filter waste and excess substances from your blood, including creatinine. This test helps doctors monitor how well they’re doing this job. Kidneys also regulate blood pressure, balance electrolytes, and support other vital functions. If your levels are abnormal, it may signal kidney disease, dehydration, or other conditions.

What Causes Changes in Creatinine Levels?

Creatinine levels can rise if your kidneys aren’t working as well as they should (e.g., due to diabetes, high blood pressure, or kidney disease). They may also drop if you’re dehydrated, have lost a lot of blood, or have muscle disorders. Certain medications or kidney-related surgeries can also affect results.

When This Test Is Ordered

Doctors often order this test to check kidney function before surgeries, during treatment for conditions like diabetes or heart disease, or if you have symptoms like swelling, fatigue, or frequent urination. It’s also part of routine check-ups for people at higher risk of kidney problems.

What to Expect Before the Test

You’ll typically have a small blood sample drawn from your arm. No special preparation is needed unless your doctor instructs otherwise. If you’re on a low-protein diet or taking certain medications, your doctor may advise adjustments.