An estimate interpreted in context
eGFR is calculated from a blood test called serum creatinine together with other information. It is a useful estimate, but it is not a direct measurement and it can be affected by factors unrelated to permanent kidney damage.
Why previous results matter
A clinician will often compare the current value with earlier results. A stable pattern, a gradual change and a sudden change can lead to very different questions. Repeat testing may be needed to confirm whether a change persists.
Why urine testing matters too
Kidney assessment commonly includes urine testing for albumin or protein and sometimes blood. A person may have an important urine abnormality even when eGFR is relatively preserved, or a reduced eGFR without substantial albumin in the urine.
What helps at a specialist review
Useful information includes earlier kidney-function and urine results, blood-pressure readings when available, a complete medication and supplement list, relevant imaging, and details about recent illness or changes in health.
When further assessment may be considered
Referral decisions depend on the full clinical picture. Examples include a persistent or progressive decline in kidney function, significant or increasing albuminuria, associated blood in the urine, difficult-to-control blood pressure, electrolyte concerns or uncertainty about the cause.
Evidence reviewed July 2026. General education only; individual interpretation belongs with the treating clinician.