eGFR — estimated Glomerular Filtration Rate

What is eGFR?

eGFR stands for estimated Glomerular Filtration Rate. The glomeruli are tiny filtering units inside the kidneys — there are approximately one million in each kidney. Together, they filter waste products, excess salts, and fluid from the blood, which are then excreted as urine. The GFR is a measure of how much blood these filters can clean per minute.

Because measuring GFR directly is complex, laboratories calculate an estimated figure (eGFR) using your serum creatinine level alongside your age and sex, applying the validated CKD-EPI formula. Creatinine is a waste product of normal muscle metabolism that the kidneys filter out continuously — if kidney function declines, creatinine accumulates in the blood and eGFR falls.

eGFR is the primary tool used by clinicians to diagnose, stage, and monitor chronic kidney disease (CKD). It is also useful for detecting acute kidney injury, monitoring patients on nephrotoxic medications, and assessing whether kidneys are safe for contrast agent use before scans.

Normal eGFR range and CKD staging

eGFR is reported in mL/min/1.73m². The following staging framework is used by NICE and UK clinical guidelines:

• ≥90 mL/min/1.73m² — Normal kidney function (CKD stage 1 only if other kidney damage markers present)
• 60–89 mL/min/1.73m² — Mildly reduced (CKD stage 2 if markers of damage present)
• 45–59 mL/min/1.73m² — Mildly to moderately reduced (CKD stage 3a)
• 30–44 mL/min/1.73m² — Moderately to severely reduced (CKD stage 3b)
• 15–29 mL/min/1.73m² — Severely reduced (CKD stage 4)
• <15 mL/min/1.73m² — Kidney failure (CKD stage 5); dialysis or transplant typically required

Note: eGFR naturally declines with age. A result in the 60–89 range in an older adult may reflect age-related decline rather than disease, particularly if no other markers of kidney damage are present.

What a low eGFR may indicate

A reduced eGFR indicates the kidneys are filtering less efficiently than expected. Possible causes include:

• Chronic kidney disease (CKD) — progressive and usually irreversible; causes include hypertension, diabetes, and glomerulonephritis
• Diabetic nephropathy — kidney damage caused by long-term poorly controlled blood sugar
• Hypertensive nephrosclerosis — kidney damage caused by sustained high blood pressure
• Acute kidney injury (AKI) — sudden decline due to dehydration, infection, NSAIDs, ACE inhibitors, or reduced blood flow to the kidneys
• Polycystic kidney disease — inherited condition causing cysts to replace kidney tissue over time

What a high eGFR may indicate

An eGFR result above 90 mL/min/1.73m² is generally considered normal and not clinically concerning. Some circumstances where eGFR may appear elevated include:

• Hyperfiltration in early diabetes — the kidneys initially work harder; eGFR may be transiently elevated before CKD develops
• High fluid intake / pregnancy — increased blood volume increases filtration rate temporarily
• Very high muscle mass — athletes with high creatinine production may have slightly different reference values
• Calculator artefact — eGFR is an estimate and very high values (>90) are typically reported as >90 rather than as a precise figure

Get your eGFR tested at The Vesey

eGFR is included in the following panels at The Vesey Private Hospital, Sutton Coldfield. It is always reported alongside serum creatinine:

• Kidney Health Panel — dedicated kidney function assessment including eGFR, creatinine, urea, uric acid
• Extended Kidney Health Panel — expanded assessment including electrolytes and protein
• Lifestyle Screen — comprehensive multi-system panel including kidney function
• Advanced Health Panels — full metabolic and organ-function assessment

No special preparation required, though staying well hydrated before the test is advisable. Results reviewed by a clinician before release.

Frequently asked questions

Further reading: eGFR — Lab Tests Online UK · Independent patient information from the British Society for Clinical Biochemistry.