Healthcare providers use estimated glomerular filtration rate (eGFR) to determine if you have kidney disease, and if so, what stage. eGFR measures your kidneys’ ability to filter toxins or waste from your blood. A very low number may indicate kidney failure, which requires dialysis or a kidney transplant.
Glomeruli are tiny filters in your kidneys that help remove toxins (waste) from your blood. Estimated glomerular filtration rate (eGFR) measures how much blood these filters clean every minute based on your body size. When you have a routine blood test, eGFR is often part of the basic metabolic panel.
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eGFR helps healthcare providers spot problems with your kidneys, including kidney disease.
Your kidneys are part of the urinary system. Kidney disease occurs when one or both kidneys have damage. When you have kidney disease, the glomeruli filter less blood. As a result, dangerous toxins can build up in your blood.
Kidney disease symptoms, such as frequent urination and muscle spasms, may not occur until you lose up to 40% of kidney function. eGFR helps providers detect the disease early so that you can start treatments to slow or stop kidney damage.
Healthcare providers use eGFR to watch for the onset of kidney disease. The test also shows the severity (stage) of existing kidney disease.
Certain health conditions increase your risk for kidney problems. Your provider may use eGFR to monitor kidney health if you have or take medications to treat:
Tests to precisely measure GFR are highly complex. For this reason, they typically only take place for research or transplant purposes. Instead, healthcare providers use a formula to come up with an estimated GFR (eGFR). The formula combines results from a serum creatinine blood test with information like your age and gender.
A serum creatinine blood test measures levels of creatinine, a waste product in your blood. Your body makes and uses creatine, a chemical, to provide energy to muscles. When muscles use this energy, muscle tissue breaks down, releasing creatinine (a toxin) into the blood. Healthy kidneys filter this toxin out of the blood and your body gets rid of it when you urinate. But when you have kidney disease, creatinine stays in the blood and gradually builds up.
To determine eGFR, your provider uses a National Kidney Foundation calculating system. This system factors in your:
The serum creatine blood test is highly sensitive. Follow your healthcare provider’s guidelines to prepare for the blood test. You may need to fast (drink only liquids and not eat solid foods) for a time before the test. You may also need to stop taking certain medications.
Your provider may also advise that you not eat cooked meat the day before the test. Some studies show that eating meat raises creatinine levels temporarily.
Healthcare providers measure eGFR in milliliters of cleansed blood per minute per body surface (a measurement that reads mL/min/1.73m2).
Values for eGFR vary depending on age, sex and other factors. The rate naturally declines as you age and lose muscle mass. The average eGFR for someone in their 20s is about 116 mL/min/1.73m2. It drops to 85 mL/min/1.73m2 for people in their 60s.
An eGFR higher than 60 means you have at least 60% kidney function. Generally, the higher the number, the better your kidney function.
Your test report may show two eGFR numbers, one for Black people and one for those who are not Black. People of African ancestry have a higher eGFR. They produce more creatinine and have more muscle mass than non-Black people. The lab doesn’t know your ethnicity or race, so the report includes both numbers.
Your provider may diagnose chronic kidney disease when your eGFR stays below 60 for three months in a row.
There are five stages:
To assess kidney damage or find the cause of an abnormal eGFR, your healthcare provider may order one or more of these tests:
If you have kidney disease or disease risk factors, call your healthcare provider if you experience:
Monitoring your eGFR is important if you’re at risk for kidney disease or already have it, including if you take certain medications. If eGFR indicates some degree of kidney disease, you can take steps to protect your kidneys from further damage. Your healthcare provider can prescribe medications to manage high blood pressure or diabetes. You can also improve kidney health by losing weight (if needed), exercising and eating a nutritious, low-salt diet.
Last reviewed by a Cleveland Clinic medical professional on 06/17/2021.
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