Glomerular Filtration Rate (GFR) Test Test
A GFR test checks how well your kidneys are working by measuring how much blood they filter each minute. It is often estimated (eGFR) using a blood test for creatinine or cystatin C.
What this test measures
A glomerular filtration rate (GFR) test is a blood test that checks how well your kidneys are working. It measures how much blood your kidneys filter each minute.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Lower-than-normal results
An eGFR that's below normal or low may mean that you may have kidney disease. A very low eGFR means that you may have kidney failure.
Frequently asked questions
What is a GFR test?
A GFR test is a blood test that checks how well your kidneys are working by measuring how much blood they filter each minute.
How is eGFR calculated?
eGFR is usually calculated using your blood creatinine level along with your age, weight, height, and sex. It can also be calculated using cystatin C levels.
What does a normal eGFR mean?
A normal eGFR means that you probably don't have kidney disease.
What does a low eGFR mean?
A low eGFR may mean you have kidney disease. A very low eGFR may mean kidney failure.
Is eGFR a perfect test?
No, eGFR is not a perfect test and may not always reflect kidney damage. It's possible to have an abnormal result even without kidney damage.
Related lab tests
Sources
- MedlinePlus: Glomerular Filtration Rate (GFR) Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.