Blood test: eGFR (estimated glomerular filtration rate)
Understanding your kidney function is an important part of maintaining your health, and the eGFR (estimated glomerular filtration rate) blood test is a key tool in the process. If you're preparing for or have recently had an eGFR test, this page provides a guide to eGFR, why it's important, and what the results can indicate about your kidney health.
- Medically reviewed by
- AKF's Medical Advisory Committee
- Last updated
- August 28, 2024
What is eGFR?
eGFR (estimated glomerular filtration rate) is a measure of how well your kidneys are working. Your eGFR is an estimated number based on a blood test and your age, sex, and body type.
eGFR is considered a mostly reliable test for doctors to know how well your kidneys are working. However, the eGFR may not be accurate if you are younger than 18, pregnant, very overweight or very muscular. In addition, other tests such as an ultrasound or a kidney biopsy may be ordered to find a cause of your kidney disease.
Previously Black race was used in the eGFR calculation along with age, sex, and body type. However, in 2021, a task force led by the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) announced recommendations to remove Black race as a factor in the eGFR calculation. While most labs have made this shift to update their lab value reports, you should check with your doctor to make sure they are not using race-based equations. Learn more about this change and what it may mean for you.
The eGFR equation uses a binary definition of gender. If you are a transgender or gender-diverse person, talk to your doctor about how you can get the best estimate of how well your kidneys are working.
How do I find out my eGFR?
You will have a blood test to see how much creatinine is in your blood. Creatinine is a waste product in your blood that comes from your muscles. Healthy kidneys take creatinine out of your blood and send it out of your body through your urine. If your kidneys are not working the way they should, creatinine will build up in your blood.
The eGFR test report will give a number that will tell doctors the amount of creatinine in your blood. You will also get a lab report that will contain this number. Be sure to talk to your doctor about what your results mean for you.
Can my eGFR change?
Your eGFR can change over time and can change based on some other problems, like if you have not been drinking enough water.
As chronic kidney disease gets worse, your eGFR number will go down. If caught early, healthy life changes like following a kidney-friendly eating plan and getting enough exercise may help slow down the progression of CKD and how fast your eGFR changes.
Can I have kidney disease even if my eGFR is normal?
Yes, your eGFR may still be in the normal range even if you have some signs of kidney damage, such as protein in your urine (pee) or physical damage to your kidneys.
If you have protein in your urine, your doctor will check you again to make sure it is not caused by something else, like being dehydrated.
Do I need to do anything to prepare for my eGFR test?
Your doctor may have you fast (not eat or drink) or avoid certain foods for several hours before the test. They will let you know how to prepare.
You may have a blood creatinine test as part of a regular check-up or if your doctor thinks you might have kidney disease. Your doctor will figure out your eGFR using your creatinine blood test result and your age, sex, weight and race.
What does my eGFR mean?
A normal eGFR is 60 or more. If your eGFR is less than 60 for three months or more, your kidneys may not be working well. Use this chart to see what your eGFR may mean.
eGFR | 90 or higher (normal range) | 60-89 (normal range) | 45-59 | 30-44 | 15-29 | Less than 15 |
|---|---|---|---|---|---|---|
| Kidney function | Normal kidney function Some signs of kidney damage, such as protein in urine (i.e., pee) or physical damage to the kidneys | Mild loss of kidney function Signs of kidney damage, such as protein in urine or physical damage to the kidneys | Moderate kidney function Sometimes, symptoms of kidney damage, such as:
| Moderate kidney function Some symptoms of kidney damage, such as:
| Severe kidney damage Symptoms of kidney damage and other health problems, such as:
| Kidneys are close to failure or have already failed People at this stage feel very sick and need dialysis or a kidney transplant to stay alive |
| Stage of kidney disease | Stage 1 | Stage 2 | Stage 3a | Stage 3b | Stage 4 | Stage 5 |
| What happens next? | Talk to your doctor about ways you can slow down the damage to your kidneys. | Talk to your doctor about ways you can slow down the damage to your kidneys. | If your eGFR was 60 or less, talk to your doctor right away! Ask when you should be tested again. If this was your first eGFR test, you may need to be tested again in a few months. Your doctor will want to see if your eGFR is 60 or less for three months or more. | If your eGFR was 60 or less, talk to your doctor right away! Ask when you should be tested again. If this was your first eGFR test, you may need to be tested again in a few months. Your doctor will want to see if your eGFR is 60 or less for three months or more. | If your eGFR was 60 or less, talk to your doctor right away! Ask when you should be tested again. If this was your first eGFR test, you may need to be tested again in a few months. Your doctor will want to see if your eGFR is 60 or less for three months or more. | If your eGFR was 60 or less, talk to your doctor right away! Ask when you should be tested again. If this was your first eGFR test, you may need to be tested again in a few months. Your doctor will want to see if your eGFR is 60 or less for three months or more. |
No matter what your eGFR is, take these steps to keep your kidneys as healthy as possible:
- Keep a healthy blood pressure (less than 120/80 for most people).
- Control your blood sugar if you have diabetes.
- Follow a healthy low-salt, low-saturated-fat eating plan.
- Do something active for at least 30 minutes most days of the week, such as walking or biking.
- Keep a weight your doctor says is healthy for you.
- Do not smoke or use tobacco.
- Ask your doctor about medicines that may help protect your kidneys.
No matter what your eGFR is, ask your doctor when you should be tested again and what other tests you should have. Your doctor may want to do other tests to look for signs of kidney problems, such as:
- Urine test for protein or blood
- Blood test for other wastes
- Blood pressure
- Blood sugar (glucose) test
How can I improve my creatinine and eGFR levels?
While no specific food or supplement can single-handedly improve kidney function or creatinine levels, Kidney Kitchen® contributor, Dr. Blake aka "The Cooking Doc®," explains what factors can affect those readings - and tips to potentially improve them! Learn about improving your creatinine and eGFR levels.
Find delicious kidney-friendly recipes
Learn what healthy eating means for people in every stage of kidney disease, including those on dialysis or living with a kidney transplant.
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