eGFR (Creatinine)
eGFR (creatinine) estimates how well the kidneys filter the blood, using creatinine, age and sex.
eGFR (creatinine) estimates how well the kidneys filter the blood. It is calculated from creatinine, a by-product of normal muscle metabolism, together with age and sex. It is the most widely used way to estimate kidney filtration. Retesting shows how it changes over time.
Because creatinine comes from muscle, very muscular people tend to get a lower estimate and very lean people a higher one. Hard training, a large meat-rich meal before the test, creatine supplements, low fluid intake and some medicines can also shift it. Filtration changes gradually with age.
Foods that help
Water through the day, water-rich vegetables and fruit, and a protein intake spread across meals from both plant and animal sources.
Foods to limit
Lots of salt, processed meat and very large protein portions shortly before the test, and creatine supplements in the days before the sample.
Track it through the year
One value is a snapshot. Following it up shows whether what you changed is working.
Related markers
Educational information only — not a diagnosis. Every result is checked against safe limits, and anything critical is escalated for follow-up.
See all 84 markers →