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. According to the KDIGO guideline, 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) |
Agree on your personal target range with your doctor.
↓ What a low value means
The KDIGO 2024 guideline divides GFR into categories. eGFR 60–89 counts as mildly decreased (G2), often without symptoms; on its own, G2 (like G1) does not meet the criteria for chronic kidney disease (CKD), which additionally requires markers of kidney damage, such as albumin in the urine, for more than three months. eGFR 30–59 (G3a/G3b): mildly to severely decreased, risk of anemia, hypertension, electrolyte imbalances. eGFR 15–29 (G4): severely decreased, early uremic symptoms possible. eGFR < 15 (G5): kidney failure. If eGFR stays below 60 for more than three months, KDIGO speaks of CKD. Common causes: diabetes, uncontrolled hypertension, chronic NSAID use, contrast nephropathy. Whether CKD is present and whether and how treatment is given is decided by your doctor.
↑ What a high value means
An apparently very high eGFR is often a calculation artifact or physiologically normal in well-trained young individuals. Glomerular hyperfiltration occurs early in diabetes mellitus and obesity and is a sign of renal stress before eGFR falls from nephron loss.
✓ What can influence this value
The eGFR is influenced by kidney diseases, high blood pressure, diabetes, fluid balance, age, and substances that burden the kidneys such as NSAIDs or contrast agents. Because the calculation is based on creatinine, muscle mass, a meat-rich meal, intense exertion, and creatine preparations can raise creatinine; the eGFR can then appear lower than it is. The assessment is made by the treating doctor.
When to test
The eGFR is mainly measured at older age and with risk factors (diabetes, hypertension, family history); how often is decided by your doctor. Fasting is not required. A meat-rich meal or intense exercise the day before and creatine supplements in the preceding days can raise creatinine temporarily and make the eGFR appear lower.
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 in healthy kidneys for the amounts studied.
When is a reduced eGFR assessed by a nephrologist? +
Reasons for a nephrology assessment include an eGFR that stays reduced for more than three months, a rapid decline, proteinuria, or an unexplained cause. Your doctor interprets the result.
GFR
Sources
Last updated: May 28, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.