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Estimated GFR

A calculated estimate of kidney filtration. Creatinine, cystatin C or both can be used; trends and clinical context help interpret the result.

GFR
Kidney Function
Measured in ml/min/1.73m²

What it measures

Estimated glomerular filtration rate (eGFR) describes how quickly the kidneys are estimated to filter blood. It is calculated from creatinine, cystatin C or both, together with factors such as age and sex. It is an estimate rather than a direct measurement.

Creatinine-based estimates can be less reliable when muscle mass or other influences on creatinine differ from the assumptions of the equation. Cystatin C is less influenced by muscle mass but has its own limitations. Combining the two markers generally improves accuracy; clinical circumstances can favour another approach.

A single eGFR does not give the whole picture of kidney health. Clinicians consider changes over time, urine albumin and other evidence. An unexpected or persistently reduced estimate should be assessed in that wider context.

What your results mean

Low

Below Range

A lower eGFR can reflect reduced filtration, but the estimate can also be affected by influences on the blood markers used to calculate it. A clinician can review previous results, urine tests, muscle mass and medicines, and consider cystatin C or further assessment where appropriate.

Normal

Within Range

An eGFR in the expected range is one part of the assessment. The estimate has limitations, including those related to muscle mass when creatinine is used. Trends and other kidney tests can add useful information.

High

Above Range

A high eGFR often reflects efficient kidney filtration, common in young adults and in early pregnancy. It can occasionally reflect hyperfiltration in the earliest stages of diabetes, so if it is markedly elevated your GP may want to review your blood sugar and overall metabolic picture.

Tests that include Estimated GFR

See where your Estimated GFR sits

A blood test that includes Estimated GFR.

View blood testsExplore all biomarkers