Serum or Plasma Creatinine Concentration (Mass Concentration)

Why Your Kidneys Matter

Your kidneys are vital organs that filter waste and excess substances from your blood, helping to maintain your body’s chemical balance. Creatinine is a byproduct of muscle metabolism that your kidneys remove from your blood. If your kidneys aren’t working well, creatinine levels can build up, which may indicate kidney problems.

What This Test Detects

Creatinine levels in your blood or plasma are measured to determine how efficiently your kidneys are filtering waste. Higher levels may suggest reduced kidney function, while lower levels might indicate overhydration or other conditions.

How the Test Works

A small blood sample is taken from your arm and sent to a lab. The lab uses a specialized method (often automated) to measure creatinine concentration. Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).

What Your Results Mean

Kidney function is often assessed alongside other tests, such as blood urea nitrogen (BUN). While creatinine alone doesn’t diagnose kidney disease, it’s a useful marker when combined with clinical symptoms and other tests. Your doctor will interpret results in the context of your overall health.