Creatinine test

A creatinine test reveals important information about your kidneys.

Creatinine is a chemical waste product that's produced by your muscle metabolism and to a smaller extent by eating meat. Healthy kidneys filter creatinine and other waste products from your blood. The filtered waste products leave your body in your urine.

If your kidneys aren't functioning properly, an increased level of creatinine may accumulate in your blood. A serum creatinine test measures the level of creatinine in your blood and gives you an estimate of how well your kidneys filter (glomerular filtration rate). A creatinine urine test can measure creatinine in your urine.

Why it's done How you prepare What you can expect Results

A serum creatinine test — which measures the level of creatinine in your blood — can indicate whether your kidneys are working properly. How often you need creatinine tests depends on any underlying conditions and your risk of kidney damage. For example:

  • If you have type 1 or type 2 diabetes, your doctor may recommend a creatinine test at least once a year.
  • If you have kidney disease, your doctor may recommend creatinine tests at regular intervals to monitor your condition.
  • If you have an illness that may affect your kidneys — such as high blood pressure or diabetes — or you're taking medication that may affect your kidneys, your doctor may recommend creatinine tests.

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