What is a normal eGFR?

An eGFR of 90 or above is generally considered normal. 60 to 89 can be normal for your age if there are no other signs of kidney damage. Your doctor reads it in context.

Should I avoid anything before an eGFR test?

Lab Tests Online UK notes NICE advice not to eat meat or fish in the 12 hours before, as it can raise creatinine. Follow the instructions you were given.

Why is eGFR estimated rather than measured?

Measuring filtration directly is complex. eGFR is calculated from a routine blood test, which is practical for everyday care.

EGFR

eGFR result explained

eGFR (estimated glomerular filtration rate) is a calculated estimate of how much blood your kidneys filter each minute, worked out from the creatinine in your blood along with your age and sex. It is reported in mL/min/1.73m², and a higher number means the kidneys are filtering more.

Why it’s confusing

It looks like a measurement, but it is an estimate from a formula. Things that change creatinine without changing the kidneys — muscle mass, a meal of meat, creatine supplements — can move it.

Results are also described in stages, and a number in a lower band can sound like a diagnosis even though a single result can’t show whether a change is lasting.

How to read it

The NHS says healthy kidneys should be able to filter more than 90 ml/min. Lab Tests Online UK sets out the bands used: 90 or above is generally normal; 60 to 89 is mildly reduced and may still be normal for your age; 45 to 59 and 30 to 44 are stages 3a and 3b of chronic kidney disease; 15 to 29 is stage 4; below 15 is kidney failure.

Doctors read eGFR with a urine test — the albumin:creatinine ratio (ACR) — and with earlier results. A lower number on its own isn’t always kidney disease, and kidney disease isn’t diagnosed from a single reading.

eGFR is less accurate in some people, including during pregnancy and in people with very high or low muscle mass. A cystatin C-based estimate is sometimes used instead.

What it does not mean

That one low result means kidney disease. Doctors look for a lasting change and other signs.
That a result of 60 to 89 is a problem by itself. It can be normal for your age when there are no other signs.
That eGFR is a percentage of kidney function. It is a filtration rate in mL/min/1.73m².

Where you’ll see it

Kidney function results, renal panels and U&Es (urea and electrolytes), alongside creatinine.
Metabolic panels (BMP or CMP) in the US.

Questions worth asking

Ask your doctor

How does this eGFR compare with my earlier results?
Do I need a urine test or a repeat blood test?
Could anything I take or eat have affected it?

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Common questions

What is a normal eGFR?: An eGFR of 90 or above is generally considered normal. 60 to 89 can be normal for your age if there are no other signs of kidney damage. Your doctor reads it in context.
Should I avoid anything before an eGFR test?: Lab Tests Online UK notes NICE advice not to eat meat or fish in the 12 hours before, as it can raise creatinine. Follow the instructions you were given.
Why is eGFR estimated rather than measured?: Measuring filtration directly is complex. eGFR is calculated from a routine blood test, which is practical for everyday care.

Sources

Reading a scan report rather than a blood test or letter? Radily’s radiology report phrase guides explain the wording radiologists use.