About estimated glomerular rate (eGFR)

Your kidneys filter your blood by removing waste and extra water to make urine. The glomerular filtration rate (GFR) shows how well the kidneys are filtering. An estimated 37 million adults in the United States may have chronic kidney disease (CKD) but nearly 90% are unaware of their condition. When found early, people can take important steps to protect their kidneys.

Measuring and estimating GFR

Getting an accurate GFR level is challenging because measured GFR (mGFR) is a complicated and lengthy process. This makes it impractical for both clinicians and patients. It is for this reason that healthcare professionals use a formula to estimate GFR. Often, CKD does not have any symptoms until the later stages of the disease. This is the reason why reliable estimates of GFR are so important for identifying CKD as early as possible.

The standard way to estimate GFR is with a simple blood test that measures your creatinine levels. Creatinine is a waste product that comes from the digestion of dietary protein and the normal breakdown of muscle tissue. Aside from CKD, creatinine levels can be affected by other factors including diet; muscle(weight of your muscles); malnutrition; and other chronic illnesses.

Differences between eGFR and mGFR

*Other factors that can affect eGFR include: pregnancy, being over the age of 70, unusual muscle mass, cirrhosis (a disease caused by scarring in the liver), nephrotic syndrome (a condition caused by having too much protein in your urine), a past solid organ transplant, and some medications.

Purpose

Why eGFR testing is done

Early-stage CKD doesn’t usually cause symptoms, but your doctor may recommend an eGFR test if you are at higher risk of developing the disease. CKD risk factors include:

Diabetes

High blood pressure

Overweight/obesity

Over the age of 60

Family history of CKD or kidney failure

Usually, developing CKD is not due to any single reason, but because of a combination of physical, environmental, and social factors.

Later stage CKD does cause symptoms. So you may need an eGFR test if you have any of the following symptoms:

Urinating more often or less often than usual

Itching

Feeling tired

Swelling in your arms, legs, or feet

Muscle cramps

Nausea and vomiting

Loss of appetite

Results

eGFR of 90 or higher is in the normal range

eGFR of 60 -89 may mean early-stage kidney disease

eGFR of 15 -59 may mean kidney disease

eGFR below 15 may mean kidney failure

What is a normal eGFR number?

In adults, the normal eGFR number is usually more than 90. eGFR declines with age, even in people without kidney disease. See chart below for average estimated eGFR based on age.

Understanding your results

There are five stages of kidney disease. Your healthcare professional determines your stage of kidney disease based on the amount of kidney damage shown by your eGFR or mGFR. Now that your know your eGFR, find out your kidney disease stage using the table below.

What are the stages of chronic kidney disease (CKD)?

What to do next

If you have any of the CKD risk factors listed above, ask your healthcare professional to order an eGFR lab test.

Questions for your healthcare team

Now that you know your eGFR and your stage of kidney disease, use this table to find questions to ask your healthcare professional at your appointments.