💡 In one sentence: eGFR is a calculated number — derived from your blood creatinine level, age, and sex — that estimates how well your kidneys are filtering waste from the blood; it is the primary measure of kidney function.
What Does eGFR Measure?
The kidneys filter approximately 180 litres of blood daily. The glomerular filtration rate (GFR) measures how much blood the kidneys can filter per minute. Because directly measuring GFR is complex, it is estimated (hence "estimated GFR" or eGFR) using a formula — the most common being the CKD-EPI equation — that uses serum creatinine (a muscle waste product), age, and sex. A normal eGFR is above 90 mL/min/1.73m². Chronic kidney disease (CKD) is defined as an eGFR below 60 mL/min/1.73m² on two occasions more than 3 months apart. The eGFR stages guide treatment decisions, monitoring frequency, and medication dosing adjustments.
Understanding Abnormal Results
⬇️ Low eGFR may indicate:
60–89 — in a young person under 40Warrants investigation for underlying kidney disease (glomerulonephritis, reflux nephropathy, hereditary kidney disease); not just age-related decline
30–59CKD stage G3 — requires nephrology involvement, cardiovascular risk reduction, dietary protein moderation, and strict blood pressure control
<30Advanced CKD — all nephrotoxic drugs stopped, dialysis planning begins, erythropoietin for anaemia; urgent nephrology care
<15End-stage kidney disease — renal replacement therapy (dialysis or transplant) is required for survival
Frequently Asked Questions
Is a low eGFR always serious?
Context matters significantly. A 75-year-old with an eGFR of 62 may simply reflect normal age-related kidney decline — with no additional kidney damage markers (protein in urine, blood in urine, abnormal kidney scan), this may be watched rather than treated. A 35-year-old with an eGFR of 62 is not normal — kidneys should function at 90+ at that age — and warrants investigation. The combination of eGFR with urine albumin-to-creatinine ratio (ACR) determines the full CKD staging.
Can eGFR improve?
In early CKD (stage 1–2), treating the underlying cause (controlling blood pressure, optimising diabetes, stopping nephrotoxic drugs) can stabilise or slightly improve eGFR. In established CKD (stage 3–4), the goal is to slow progression rather than reverse it — strict BP control (target below 130/80), ACE inhibitors or ARBs to reduce protein loss, and dietary modifications. Once eGFR falls below 15, only dialysis or transplant maintains survival.
My creatinine is 120 — what does that mean?
Creatinine alone without context is hard to interpret — a creatinine of 120 µmol/L in a large muscular man may be normal, but in a small elderly woman it could indicate significant kidney impairment. This is why eGFR — which accounts for age, sex, and body size — is more useful than creatinine alone. Ask your doctor for the eGFR alongside the creatinine value.
What medications damage the kidneys and should I avoid?
Key nephrotoxic medications to use cautiously or avoid in reduced eGFR: NSAIDs (ibuprofen, diclofenac, indometacin — reduce kidney blood flow), gentamicin and other aminoglycoside antibiotics (direct tubular toxicity), contrast dye for CT scans (contrast nephropathy), ACE inhibitors in bilateral renal artery stenosis, and certain traditional herbal preparations (many contain aristolochic acid — a potent nephrotoxin common in West African herbal remedies). Always inform every prescribing doctor of your kidney function results.