What is eGFR & normal range

Glomerular filtration rate (GFR) is a measure of the function of the kidneys. This test measures the level of creatinine in the blood and uses the result in a formula to calculate a number that reflects how well the kidneys are functioning, called the estimated GFR or eGFR.

The eGFR is a calculation based on a serum creatinine test. Creatinine is a muscle waste product that is filtered from the blood by the kidneys and released into the urine at a relatively steady rate. When kidney function decreases, less creatinine is eliminated and concentrations increase in the blood. With the creatinine test, a reasonable estimate of the actual GFR can be determined.

Different equations may be used to calculate eGFR. The following two are most common and require a person’s blood creatinine result, age, and assigned values based upon sex and race.

  • Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation (2009)—recommended by the National Kidney Foundation for calculating eGFR in adults
  • Modification of Diet in Renal Disease Study (MDRD) equation—some laboratories continue to use this equation

The results reported using one equation versus the other will not be identical but should give a healthcare practitioner similar information.

A different set of CKD-EPI calculators was published in 2012. These equations use the result of a cystatin C test. (For more on these, see Common Questions below.) There is also a modified equation for people 18 and under that takes the blood urea nitrogen (BUN) level into consideration along with the factors listed above.

Estimated GFR results are reported as milliliters/minute/1.73m2 (mL/min/1.73m2). Because some laboratories do not collect information on a patient’s race when the sample is collected for testing, they may report calculated results for both African Americans and non-African Americans. The healthcare practitioner uses the result that applies to the particular patient in order to interpret the results correctly.

A normal eGFR for adults is greater than 90 mL/min/1.73m2, according to the National Kidney Foundation. (Because the calculation works best for estimating reduced kidney function, actual numbers are only reported once values are less than 60 mL/min/1.73m2).

An eGFR below 60 mL/min/1.73m2 suggests that some kidney damage has occurred. The test may be repeated to see if the abnormal result persists. Chronic kidney disease is diagnosed when a person has an eGFR less than 60 mL/min/1.73m2 for more than three months.

A person may have some kidney damage even with an eGFR greater than 90 mL/min/1.73m2. Other evidence, such as increased urine albumin, may indicate some degree of kidney damage. Thus, a person’s eGFR should be interpreted in relation to the person’s clinical history and presenting conditions.

The following table summarizes estimated GFR and the stages of kidney damage:

Kidney damage stage description estimated gfr (ML/MIN/1.73M2) other findings
1 Normal or minimal kidney damage with normal GFR 90+ Protein or albumin in urine may be high, cells or casts rarely seen in urine (see Urinalysis)
2 Mild decrease in GFR 60-89 Protein or albumin in urine may be high, cells or casts rarely seen in urine
3 Moderate decrease in GFR 30-59
4 Severe decrease in GFR 15-29
5 Kidney failure <15
* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.