Serum or plasma concentration of creatinine (mass concentration)

Why This Test Matters

Creatinine levels help doctors assess kidney function by measuring how efficiently your kidneys filter waste products like creatinine from your blood. Healthy kidneys remove creatinine and other waste products through urine. If levels are too high, it may indicate kidney problems or reduced kidney function.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood draw or urine sample collected, depending on the type of creatinine test being done. If it’s a blood test, you’ll likely sit or lie down while a healthcare provider inserts a small needle into a vein in your arm.

What the Results Mean

Results are compared to a reference range that varies by lab and age. High levels may signal kidney issues, while low levels could suggest dehydration or muscle breakdown. Your doctor will interpret results in relation to your overall health and symptoms.

Common Causes of Abnormal Results

High creatinine levels can be caused by kidney disease, dehydration, or conditions that increase muscle breakdown (e.g., severe illness or injury). Low levels may occur with dehydration, overhydration, or muscle loss. Other factors like diet, medications, or certain medical conditions can also affect results.