eGFR
An estimate of how well your kidneys are filtering, which declines naturally with age.
What it means
An estimate of how much blood your kidneys filter each minute, calculated from a blood creatinine level along with your age and sex. Above 90 is considered normal.
The important thing: eGFR falls naturally with age. A figure of 60 in a healthy 75-year-old is often entirely normal for them, while the same figure in a 30-year-old would need investigating.
It is an estimate, not a measurement — and it is affected by muscle mass, so it reads low in very muscular people and high in frail ones.
In practice
On almost any routine blood test, reported alongside creatinine. It appears on health screens, medication monitoring bloods and hospital results.
Often accompanied by a "CKD stage", which is where the alarm usually starts — "stage 3 kidney disease" sounds far worse than a stable eGFR of 55 usually is.
Why it matters
Do not act on one reading. A single low result needs repeating after about three months before it means anything.
Ask about your urine ACR. The urine protein test predicts what happens next considerably better than the eGFR does, and a normal one alongside a stable eGFR is genuinely reassuring.
Ask whether any of your medicines need the dose adjusting, which is the practical consequence that actually matters.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 30, 2026