GFR
Glomerular filtration rate as a measure of kidney function
Also known as
Definition
The glomerular filtration rate (GFR) describes the volume of plasma filtered by the renal glomeruli per minute and is the primary measure of kidney function. In practice, eGFR is calculated from creatinine, age, and sex using the CKD-EPI formula. A value below 60 ml/min/1.73 m² persisting for more than three months defines chronic kidney disease.
| Parameter | Value |
|---|---|
| Unit | ml/min/1.73 m² |
| Reference Range | > 90 ml/min/1.73 m² (normal kidney function) |
| Optimal Range (lab2go) | > 90 ml/min/1.73 m² |
↓ What a low value means
eGFR 60–89: mildly reduced kidney function (CKD grade G2), often asymptomatic. eGFR 30–59: moderate impairment (CKD grade G3a/G3b), risk of anemia, hypertension, electrolyte imbalances. eGFR 15–29: severe impairment (CKD grade G4), uremia pre-symptoms possible. eGFR < 15: kidney failure (CKD G5), dialysis/transplant consideration. Common causes: diabetes, uncontrolled hypertension, chronic NSAID use, contrast nephropathy.
↑ What a high value means
Apparent very high eGFR (> 120 ml/min/1.73 m²) is often a calculation artifact or physiologically normal in well-trained young individuals. Glomerular hyperfiltration (> 135 ml/min/1.73 m²) occurs early in diabetes mellitus and obesity and is a sign of renal stress before eGFR falls from nephron loss.
✓ How to optimize this marker
For impaired eGFR: adequate fluid intake (1.5–2 l/day); minimize NSAID use; maintain blood pressure < 130/80 mmHg; normalize blood glucose; adjust protein intake in CKD G3+ (0.6–0.8 g/kg/day with nephrology guidance). Avoid nephrotoxic substances. Creatine supplementation computationally lowers eGFR — it can appear falsely low.
When to test
Annual screening from age 60 or with risk factors (diabetes, hypertension, family history). No fasting required; avoid high-meat meals and intense exercise the day before (transient creatinine rise). Pause creatine supplements 48–72 hours before for a representative measurement.
Frequently asked questions
What is the difference between eGFR and measured GFR? +
True GFR is measured with inulin clearance or radioactive markers — complex and only performed in specialty labs. eGFR is a calculated estimate from creatinine, age, and sex (CKD-EPI formula) and is sufficiently precise for clinical practice.
Does creatine supplementation harm kidney function? +
Creatine raises serum creatinine (through metabolism to creatinine) without impairing true kidney function. eGFR appears computationally lower. No kidney damage is documented at normal doses (3–5 g/day) in healthy kidneys.
At what eGFR should I see a nephrologist? +
With eGFR < 60 ml/min/1.73 m² persisting for more than 3 months, rapid decline (> 5 ml/min/year), proteinuria, or unexplained cause, nephrology referral is indicated.
Sources
Last Reviewed: May 28, 2026 · sina
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.