What is eGFR and what does it measure?
eGFR estimates kidney filtration capacity from creatinine, age, and sex. Values ≥90 mL/min/1.73m² are normal; persistent <60 indicates chronic kidney disease. Trend matters more than any single value.
Full answer
eGFR (estimated glomerular filtration rate) is the primary operational marker of kidney function. It is calculated from serum creatinine, age, and sex (with cystatin C as a more accurate optional input). Values ≥90 mL/min/1.73m² are considered normal; 60-89 mildly decreased; <60 sustained for ≥3 months defines chronic kidney disease. The critical insight: a single eGFR value is less informative than the trend. A stable eGFR of 70 is reassuring; a declining eGFR from 90 to 75 over two years warrants nephrology context. eGFR informs medication dosing across most chronic conditions and is required at baseline before initiating GLP-1 therapies, NSAIDs, or hormone optimization that may impact volume status.
Educational. Not a substitute for individualized provider review.
- eGFR — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29