Creatinine Test (Kidney Function)
Reviewed
A creatinine test measures a muscle-related waste product used with other information to assess kidney filtration.
Preparation and collection
The clinician or laboratory may advise avoiding cooked meat or fasting when creatinine is part of another panel. Do not stop medicines unless instructed.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- eGFR is an estimate and may be less reliable in unusual muscle mass or rapidly changing kidney function.
- Meat intake, supplements, intense exercise, hydration, and medicines can affect creatinine.
What to do next
Follow-up may include repeat creatinine/eGFR, urine albumin-to-creatinine ratio, electrolytes, imaging, or urgent assessment depending on the change and symptoms.
Evidence source
U.S. National Library of Medicine: Creatinine Test (Kidney Function)