What eGFR Actually Measures
The kidneys' filtering units, glomeruli, clear waste products like creatinine from the blood. Because measuring filtration directly is impractical, equations estimate it from serum creatinine, the CKD-EPI 2021 equation is the current standard.
Creatinine rises as filtration falls, but it also scales with muscle mass, which is why age and sex enter the equation. Very muscular people can show modestly low eGFR with perfectly healthy kidneys.
The Five Stages
Kidney disease is staged by eGFR: G1 ≥ 90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 below 15. Stages G1–G2 need no diagnosis without other damage markers.
A diagnosis of CKD requires eGFR below 60 for three months or more, or markers like albumin in the urine at any eGFR, a single low reading is a prompt to recheck, not a verdict.
Protecting Your Kidneys
Blood pressure and diabetes cause most kidney failure, so the two highest-yield habits are the same as for the heart: keep BP controlled and blood glucose in range.
Hydration helps, but the neglected killers are routine NSAID overuse, excessive salt, and smoking. Yearly eGFR and urine albumin checks catch decline early, when it's most reversible.
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FAQ
What is a normal GFR?
90 mL/min/1.73 m² or above. Values of 60–89 are usually acceptable in older adults without other signs of kidney damage.
What GFR level indicates kidney disease?
eGFR below 60 for three months or more, or urine albumin elevation at any eGFR, may indicate CKD, confirm with a clinician.
Can eGFR improve?
It fluctuates with hydration and health. True improvement comes from controlling blood pressure and diabetes and stopping kidney-straining medications.
A note before you begin: this tool offers educational estimates only. It cannot replace advice from your doctor or another qualified professional.