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Estimated glomerular filtration rate (eGFR) is a calculated measure of kidney function that estimates how well the kidneys filter waste from the blood. It is widely used to screen for kidney disease, stage chronic kidney disease (CKD), monitor progression, and guide medication dosing and other treatment decisions. eGFR values are reported as milliliters per minute per 1.73 square meters (mL/min/1.73 m^2) of body surface area.

How eGFR is calculated

eGFR is derived from serum creatinine measurements, typically using patient factors such as age, sex, and sometimes race. Commonly used equations include the MDRD and CKD-EPI formulas; cystatin C–based estimates are also available. The result is an estimate rather than a direct measurement of kidney filtration. In some laboratories, the race coefficient is included in the calculation, while other guidelines and labs report estimates without race adjustments.

Interpretation and use

Lower eGFR values indicate reduced kidney function. CKD is staged based on eGFR ranges, often together with markers of kidney damage such as proteinuria. eGFR informs diagnosis, prognosis, and management, including decisions about imaging, referrals, and adjustments to medications that are cleared by the kidneys. It is also used to monitor progression over time and to determine eligibility for certain therapies.

Limitations and considerations

eGFR is not a direct measurement of glomerular filtration rate and may be inaccurate in certain situations. It can be affected by acute kidney injury, extreme muscle mass or diet, fluid status, and pregnancy. Age and sex influence eGFR independently of kidney function, and race adjustments remain a subject of ongoing discussion. In some cases, clinicians may use cystatin C–based estimates or direct measurement methods for clarification.