Kidney function
How well your kidneys filter your blood.
eGFR + cystatin C
5 min
Metabolism & blood
Sample reading
Ages 40–49
96
mL/min
Low < 60
Mild 60–90
Normal ≥ 90
Illustrative ranges. Your physician sets yours.
(01) How it’s done
On the day
Calculated from two blood markers, creatinine and cystatin C, with a urine test for protein.
Using both markers gives a more accurate reading for people with a lot of muscle, who can look worse on creatinine alone.
(02) Why it matters
What it tells us
Kidney function falls quietly with age, blood pressure and blood sugar, with no symptoms until much has been lost.
Catching the slope early lets us protect it, mostly by bringing blood pressure down and avoiding the medicines that strain the kidneys.
(03) Same system
Metabolism & blood
Measured on the same day, read by the same physician.
