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Glomerular Filtration Rate Test

Medically reviewed by Last updated on Oct 31, 2022.

What is a glomerular filtration rate test?

A glomerular filtration rate (GFR) test shows how well your kidneys are working. It may be done to diagnose or monitor chronic kidney disease. A blood test will be done to measure the amount of creatinine in your blood. This level of creatinine is used in a formula to calculate the GFR. Other factors are used to calculate GFR. These include age, gender, weight, height, and race.

How do I get ready for the test?

Healthcare providers may tell you not to eat or drink anything, except water, after midnight. You may also be asked not to eat any cooked meat the night before the test. It can increase the level of creatinine in your blood and affect your GFR results. Ask your healthcare provider if you should take your medicines on the day of your test. Wear a short-sleeved or loose shirt on the day of the test. This will make it easier to draw your blood.

What do I need to know about my test results?

  • A normal GFR for adults is greater than 90 mL/min/1.73m² if there are no other signs of kidney damage.
  • A level between 60 and 89, along with other signs of kidney damage may mean you have early kidney disease. For example, protein in your urine is another sign of kidney damage. Your healthcare provider may order tests to measure the amount of protein in your urine.
  • A GFR below 60 may be a sign of kidney disease. You may need other tests or another GFR test if your test result remains low. A GFR that remains below 60 for 3 months or more means you have moderate to severe chronic kidney disease.
  • A GFR below 15 means you have kidney failure.

What should I do if I get abnormal test results?

Your healthcare provider will discuss your test results with you and tell you what to do next. You may need to have other tests. If you have chronic kidney disease, you will need regular GFR tests to monitor your condition. You will also need to receive treatment for kidney disease.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your lab tests. You can then discuss the results with your healthcare providers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.