Also seen on reports as: GFR (estimated), Estimated GFR, eGFR CKD-EPI, eGFR MDRD
What is eGFR?
eGFR (Estimated Glomerular Filtration Rate) is a calculated number that estimates how much blood the kidneys are filtering each minute. It is not measured directly from a separate test — it is calculated from the blood creatinine level along with age and sex (and historically sometimes race), using one of several established formulas (CKD-EPI is the most common today; MDRD was widely used previously).
Because eGFR is calculated rather than measured, it depends entirely on the inputs being accurate. The biggest source of variation is muscle mass: people with very high or very low muscle mass do not fit the assumptions the formula was built on, and the eGFR estimate becomes less reliable for them.
Most NABL-accredited Indian labs report eGFR alongside creatinine automatically. The value is expressed in millilitres per minute per 1.73 m² of body surface area (mL/min/1.73 m²) — a normal adult is roughly 90 or higher.
Why doctors order it
eGFR is not separately ordered — it is calculated from the same creatinine result and appears on the lab report alongside it. Almost every routine blood-test panel in India that includes creatinine also reports eGFR.
eGFR is the main number doctors use to stage chronic kidney disease (CKD) and to decide how aggressively to investigate or treat. The CKD stages (1 through 5) are defined largely by eGFR ranges, alongside urine findings.
It is also used to decide whether common medications and contrast dyes are safe to use at standard doses, or whether they need dose adjustment or avoidance — particularly for many antibiotics, anti-diabetic medications, anti-hypertensives, and chemotherapy.
What the result means
An eGFR of 90 or above is generally considered normal kidney filtering — though this alone does not rule out kidney disease, particularly if there is protein in the urine, structural abnormalities on ultrasound, or other markers of kidney injury. An eGFR between 60 and 89 may be normal for age in some people; it is considered mildly decreased and needs context to interpret.
Persistently low eGFR (below 60 for three months or more) is part of the definition of chronic kidney disease. The CKD stages step down from there — stage 3 (eGFR 30–59), stage 4 (15–29), and stage 5 (below 15, often called end-stage kidney disease).
eGFR can change acutely — for example, with severe dehydration, with medications that affect kidney blood flow, with very high blood pressure, or with sudden urinary obstruction. Acute changes need different work-up from chronic changes; doctors interpret eGFR alongside the trend, urine tests, and clinical picture.
Reference range
Values in mL/min/1.73 m²
- Stage G1 — normal or high
- eGFR ≥90 — kidney disease only if urine or imaging abnormalities present
- Stage G2 — mildly decreased
- eGFR 60–89 — may be normal for age; interpret with urine and clinical context
- Stage G3a — mildly to moderately decreased
- eGFR 45–59 — formal CKD; needs follow-up
- Stage G3b — moderately to severely decreased
- eGFR 30–44
- Stage G4 — severely decreased
- eGFR 15–29 — pre-dialysis planning may be needed
- Stage G5 — kidney failure
- eGFR <15 — usually requires dialysis or transplant planning
eGFR formulas (CKD-EPI / MDRD) were largely developed and validated in Western populations. Indian adults often have lower muscle mass than Western reference populations, which means these formulas can overestimate true kidney function in some Indians. There is no widely-adopted Indian-specific eGFR equation in routine use; doctors interpret eGFR in clinical context alongside creatinine, urine tests, and (in some situations) cystatin-C-based eGFR.
Common factors that affect the result
Indian-specific interpretation matters. The CKD-EPI and MDRD equations were developed and validated mainly in Western populations with different average muscle mass. Indian adults — particularly women, the elderly, and people with chronic illness — often have lower muscle mass than those reference populations. This can cause the formula to overestimate true kidney function in some Indians, meaning a 'normal' eGFR can sometimes hide an early kidney problem.
Because eGFR is calculated from creatinine, everything that affects creatinine also affects eGFR. High muscle mass, intense recent exercise, creatine supplements, and high-protein diets nudge creatinine up — and eGFR down — without true kidney injury. Low muscle mass from age, illness, or weight loss nudges creatinine down and eGFR up, without truly better kidney function.
Acute factors that change blood flow to the kidney — severe dehydration, heart failure, low blood pressure, urinary obstruction — drop eGFR temporarily. These pre-renal drops usually recover once the underlying problem is corrected. Some doctors use cystatin-C-based eGFR in tricky cases (very high or very low muscle mass, or where Indian-specific concerns apply) — cystatin C is less dependent on muscle mass.
When to talk to your doctor
- Your eGFR has dropped below 60 mL/min/1.73 m² for the first time, particularly if a previous result was higher.
- Your eGFR is between 60 and 89 with protein in the urine, structural abnormalities on ultrasound, diabetes, or hypertension — these combinations meet the CKD definition even with eGFR not yet 'low'.
- Your eGFR has dropped sharply over weeks to months, regardless of where it sits in the range — a rapid drop usually needs evaluation for acute kidney injury.
- You are starting a medication or contrast dye and your eGFR is being checked to confirm safe dosing — common examples include metformin, certain antibiotics, anti-cancer drugs, and CT-scan contrast.
- You have diabetes, hypertension, recurrent kidney stones, or a family history of kidney disease and want to discuss whether your eGFR trend over time is moving in a concerning direction.
Related tests
Sources
- Indian Society of Nephrology — CKD Clinical Practice Guidelines — Indian Society of Nephrology
- ICMR CKD Screening Guidelines — Indian Council of Medical Research
- KDIGO 2024 Clinical Practice Guidelines for CKD — Kidney Disease: Improving Global Outcomes
- AIIMS Nephrology Clinical Protocols — All India Institute of Medical Sciences
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