eGFR (estimated glomerular filtration rate)
eGFR, the estimated glomerular filtration rate, is an estimate of how much blood the kidneys filter per minute. It isn’t measured directly: the lab calculates it from creatinine, sometimes cystatin C, with age and sex.
At a glance
- Sample
- Blood
- Units
- mL/min/1.73 m²
- Often looked at with
- Creatinine, Urea, Urea nitrogen (BUN), Uric acid
- Preparation
- You may be asked to fast or not to eat meat for several hours before the test: eGFR is calculated from creatinine, and meat raises creatinine for a while.
Units
eGFR is printed in millilitres per minute per 1.73 m² of body surface (mL/min/1.73 m²), the same way in the US and in Europe, so there is nothing to convert.
Why lab ranges differ
Each lab sets its reference range for its own method and analyser, and many ranges differ by age and sex. Two labs can print different ranges for the same blood, so a result is read against the range on its own report, not against a number from another lab or a website.
Soma charts every eGFR result against the range printed by the lab that measured it.
What can affect the result
- It is calculated from creatinine, so the same things affect it: meat, intense exercise, creatine supplements.
- Muscle mass: a lot of muscle gives a lower estimate, little muscle a higher one.
- Pregnancy.
- Different formulas give different numbers.
If something like this applies, mention it to the doctor who reads your results.
Questions
Why does my lab’s eGFR range differ from another lab’s?
Each lab sets its range for its own method and equipment, and many ranges differ by age and sex. That’s why a result is best read against the range printed on the same report.
How do I prepare for an eGFR test?
You may be asked to fast or not to eat meat for several hours before the test: eGFR is calculated from creatinine, and meat raises creatinine for a while. Follow your lab’s instructions.
Related tests
Got a lab report with eGFR?
Share it to Soma: it reads every row on your phone, with no account and no upload, and puts your eGFR on one chart with your earlier results, each against the range your lab printed.
Sources
- Estimated Glomerular Filtration Rate (eGFR) and GFR Tests — MedlinePlus, U.S. National Library of Medicine.
- Estimated Glomerular Filtration Rate (eGFR) — National Kidney Foundation.
Mention of a source doesn’t mean it endorses Soma. This page explains the test; it doesn’t diagnose and is not medical advice. Talk to your doctor about what your results mean.