creatininaeGFR

Creatinine-based estimated glomerular filtration rate (eGFR) is a calculation used to infer kidney function from the concentration of creatinine in the blood. It provides an estimate of glomerular filtration rate normalized to a standard body surface area (1.73 m2) and is expressed in milliliters per minute per 1.73 square meters (mL/min/1.73 m2).

eGFR is derived from serum creatinine measurements using equations such as the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) or the older MDRD study equation. These equations incorporate serum creatinine and patient factors that influence creatinine production, typically age, sex, and race. Some laboratories report eGFR automatically together with the creatinine value.

Interpretation and use: eGFR is used to assess kidney function, stage chronic kidney disease (CKD) from G1 to G5, and guide decisions on medication dosing, diagnostic workups, and prognosis. An eGFR above 90 mL/min/1.73 m2 is often considered normal, though age-related decline can occur. It is important to note that eGFR is an estimate and may be unreliable in certain populations or clinical situations.

Limitations: The accuracy of eGFR depends on stable kidney function and precise creatinine measurement. Muscle mass, diet (notably high meat intake), hydration, and medications that affect creatinine secretion can bias results. eGFR is less reliable in acute kidney injury or in individuals with abnormal body composition, children, elderly adults, or those with very low or high muscle mass. In some cases, cystatin C–based estimates or direct measurement of GFR may be preferred.

Relation to creatinine clearance: Creatinine-based eGFR has largely supplanted timed urine creatinine clearance as a practical measure of kidney function due to greater convenience and standardization.