Creatinine is a waste product that forms each time you use your muscles. Healthy kidneys remove creatinine from the blood. Higher than normal levels may mean that you have a lot of muscle mass—or that your kidneys are not working well.
Normal creatinine levels are:
- Adult males: 0.8 – 1.4 mg/dL
- Adult females: 0.6 – 1.1 mg/dL
A creatinine blood test is a routine part of a medical checkup. Your creatinine, age, sex, and race can be used to find your estimated glomerular filtration rate (eGFR). Your eGFR is a way to learn how much kidney function you have.
Your eGFR is only as accurate as your creatinine level. The National Kidney Disease Education Program (NKDEP) studied how laboratories measure creatinine. In 2006, they chose a standard method. You can learn about it at: www.nkdep.nih.gov/labprofessionals/
Getting accurate results
If your body makes more or less creatinine than the average person an eGFR level may not show your true level of kidney function. An eGFR calculator may not give you the right result if you are:
- Under age 18
- Older than age 70
- Very overweight
- Very muscular
- Very malnourished
- A vegetarian
- Taking creatine supplements for body building
Always share an eGFR result with your doctor, who may want to do more tests. In some cases, your doctor might want to:
- Do another blood test to double-check your creatinine and eGFR
- Check a urine sample to see if there is protein in your urine
- Measure how much urine you are making each day (a 24-hour urine test)
- Order an ultrasound, CT scan, or MRI to “look” at your kidneys
Learn more about the 5 stages of chronic kidney disease.