What is eGFR?

eGFR, estimated glomerular filtration rate, is one of the most important numbers for understanding your kidney health. Here’s what it measures, what your result means, and what to do next.

What does eGFR measure?

Each kidney holds about a million tiny filters called glomeruli, which clear waste and extra fluid from your blood. Your eGFR estimates how much blood those filters clean each minute, adjusted for body size (reported as mL/min/1.73m²). It is the best single measure of overall kidney function.

How is eGFR calculated?

You don’t measure eGFR directly. Instead, a routine blood test measures creatinine, a waste product, and that value is combined with your age and sex in a validated formula (the current standard is the CKD-EPI 2021 equation) to estimate your filtration rate. This newer equation no longer uses a person’s race, a change adopted across U.S. labs in recent years so that everyone is assessed the same way. Because it is an estimate, your eGFR can shift slightly from test to test, and the trend over time matters more than any single reading.

What do my eGFR results mean?

Generally, a higher eGFR means better kidney function. Common ranges are:

• 90 or above, normal kidney function (this is only chronic kidney disease if there are other signs of damage, such as protein in the urine).
• 60–89, mildly reduced; often still normal if there are no other signs of kidney damage.
• 45–59 (Stage 3a) and 30–44 (Stage 3b), moderately reduced kidney function.
• 15–29 (Stage 4), severely reduced.
• Below 15 (Stage 5), kidney failure, where dialysis or a transplant may be considered.

A single low number is not a diagnosis. Chronic kidney disease is generally diagnosed when eGFR stays below 60, or there are other markers of kidney damage, for at least three months. Your nephrologist looks at your eGFR alongside urine tests and your overall health. Learn more about the stages of kidney disease.

What can affect my eGFR result?

A few everyday things can temporarily change your result: dehydration, a recent high-protein or large meat meal, certain medications, and acute illness. Muscle mass also plays a role, because creatinine comes from muscle. This is why doctors usually repeat the test and watch the pattern rather than react to one value.

What should I do about my eGFR?

If your eGFR is low or trending down, the most protective steps are usually keeping blood pressure and blood sugar well controlled, reviewing your medications with your doctor, staying hydrated, and following a kidney-friendly eating plan. A nephrologist can determine the cause, confirm whether you have chronic kidney disease, and build a plan to protect the kidney function you have.

This article is for general education and is not a substitute for personalized medical advice. Talk with your doctor or nephrologist about your specific situation.