Biomarker guide
eGFR (mL/min/1.73m²)
eGFR (estimated glomerular filtration rate) estimates how many milliliters of blood your kidneys filter per minute, calculated from blood creatinine along with age and sex. It is the standard measure of kidney function, and people test it because kidney decline is typically silent until it is advanced.
Reference ranges
Commonly used adult reference ranges. Labs vary in methodology and cutoffs, interpret your results against your lab report's stated ranges and with your doctor.
For eGFR, lower is worse: 90+ is consistent with full kidney function, while sustained values below 60 are the commonly used threshold of concern.
| Zone | Range |
|---|---|
| Kidney failure range | 0–15 mL/min/1.73m² |
| Reduced | 15–60 mL/min/1.73m² |
| Mildly reduced | 60–90 mL/min/1.73m² |
| Optimal | 90–120 mL/min/1.73m² |
The importance of eGFR
The kidneys filter roughly 180 liters of blood a day[1], clearing waste and balancing fluids, electrolytes, and blood pressure. eGFR estimates that filtration capacity, and unlike most markers on this site, lower is worse: values above 90 are consistent with full function, while sustained values below 60 define chronic kidney disease staging.[2]
Kidney function declines silently, most people feel nothing until the majority of function is gone[3], which is why eGFR appears on routine metabolic panels. A gradual drift downward across years matters more than any single reading, and the trend is especially worth watching for people with diabetes, high blood pressure, or a family history of kidney disease.
eGFR is an estimate with known blind spots: high muscle mass, creatine supplements[4], a large meat meal before the draw, and dehydration can each depress the calculated value without any true kidney change. An unexpectedly low result is usually repeated, sometimes with a cystatin C–based estimate or a urine albumin test, before conclusions are drawn[5], a follow-up path worth discussing with your doctor.
Part of our complete guide to Organ Health Lab Tests — browse every panel and biomarker guide in this hub.
Frequently asked questions
What is a normal eGFR?
An eGFR of 90 mL/min/1.73m² or higher is consistent with normal kidney function in adults, and 60–89 is common with age and usually unremarkable without other findings. Sustained values below 60 for three months or more are the commonly used threshold for chronic kidney disease staging.
Can eGFR be low without kidney disease?
Yes. Because eGFR is calculated from creatinine, a muscle byproduct, high muscle mass, creatine supplementation, a meat-heavy meal before the draw, and dehydration can each lower the estimate without any true change in kidney function. A repeat test, sometimes using cystatin C instead, usually clarifies.
Does eGFR decline with age?
Gradually, yes, average eGFR falls roughly 1 mL/min per year after about age 40, so a value in the 60s–80s is common in older adults without disease. The rate of decline matters more than the absolute number, which is why year-over-year comparison is the most useful way to read it.
What helps protect kidney function?
The biggest levers are the ones that protect blood vessels: keeping blood pressure and blood sugar in range, not smoking, staying hydrated, and using NSAIDs (like ibuprofen) sparingly. People with diabetes or hypertension benefit most from regular eGFR and urine-albumin monitoring, on a schedule set with their doctor.
References
- [1] Physiology, Glomerular Filtration Rate — StatPearls, NCBI Bookshelf (NIH)
- [2] Stages of Chronic Kidney Disease (CKD) — National Kidney Foundation
- [3] What Is Chronic Kidney Disease in Adults? — NIDDK (NIH)
- [4] Is It Time for a Requiem for Creatine Supplementation-Induced Kidney Failure? A Narrative Review — Nutrients
- [5] Estimated GFR (eGFR) Test: Kidney Function Levels, Stages, and What to Do Next — National Kidney Foundation
Reviewed by
Jason August
Founder & Editorial Lead
Jason August is the founder of Metabolic Markers and its parent company, Advancing Development. He has spent his career building and scaling real-world ventures, including as a founding team member at Build-A-Bear Workshop during its growth from startup to global public company, and since then across capital, real estate, adaptive reuse, and hospitality. He founded Metabolic Markers to make blood-biomarker testing easier to understand and access, and oversees the site’s content and editorial accuracy. Jason is not a medical professional; all content on this site is educational, reviewed for accuracy, and never a substitute for advice from a licensed physician.
Panels that measure eGFR
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