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 check if your kidneys are working properly by measuring how well they remove creatinine from your bloodstream. Healthy kidneys efficiently filter creatinine, so higher levels in your blood may suggest impaired kidney function.

What Causes Changes in Creatinine Levels?

Several factors can affect creatinine levels, including dehydration, muscle mass (more muscle = higher creatinine), certain medications, or kidney disease. If your levels are unusually high, your doctor may investigate further to rule out conditions like kidney damage or fluid imbalance.

When Might You Need This Test?

Doctors often order creatinine tests as part of a general health check, to monitor kidney function before or after treatments (like chemotherapy), or if you have symptoms like swelling, fatigue, or changes in urination. It’s also used to track kidney health in chronic conditions like diabetes or high blood pressure.

What to Expect During the Test

This test is usually done by drawing blood from a vein in your arm. You may feel a small pinch, but it’s quick and doesn’t require special preparation. If you’re on dialysis or have a history of kidney issues, your doctor may adjust how often you get this test.