eGFR test: normal range, kidney stages and what the number means

An eGFR test is not a separate measurement. It is an estimate of how much blood the kidneys filter each minute, calculated from a creatinine result together with age and sex, and reported in millilitres per minute per 1.73 m² of body surface. It is the number kidney guidelines use to describe kidney function in stages.

What it measures

The glomerular filtration rate (GFR) is the volume of blood the kidneys' filtering units clear each minute. Measuring it directly means giving a marker substance and timing how fast it is cleared, which NICE suggests where a highly accurate figure is needed, such as assessing a possible kidney donor. Everyday practice estimates it from creatinine instead, and the result is the eGFR.

Because it comes from creatinine, eGFR assumes ordinary muscle mass and steady kidney function. NIDDK stresses that it is an estimate, not a precise measure: when the current equation was tested, about 87 in 100 estimates fell within 30% of measured GFR.

How it is calculated

The equation that US kidney bodies recommend, and that NIDDK expects to become the most widely used, is the 2021 CKD-EPI creatinine equation. It uses creatinine, age and sex, and unlike earlier versions it does not use race. In conventional units it reads:

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.200 × 0.9938^age × 1.012 (if female)

Scr is creatinine in mg/dL (divide µmol/L by 88.4), κ is 0.7 for women and 0.9 for men, and α is -0.241 for women and -0.302 for men. The age term does a lot of the work. For a man with a creatinine of 1.0 mg/dL (88 µmol/L), the equation gives about 98 at age 40 and about 81 at age 70, with no change in the blood result.

Normal range and stages

KDIGO, the international kidney guideline group, sorts GFR into six categories:

Category	eGFR (mL/min/1.73 m²)	Description
G1	90 or above	Normal or high
G2	60 to 89	Mildly decreased
G3a	45 to 59	Mildly to moderately decreased
G3b	30 to 44	Moderately to severely decreased
G4	15 to 29	Severely decreased
G5	Below 15	Kidney failure

G1 and G2 on their own are not kidney disease: without other signs of kidney damage, such as albumin in the urine, they do not meet the definition, and chronic kidney disease requires a change lasting at least three months. MedlinePlus, citing the National Kidney Foundation, gives 90 to 120 as a normal result, lower with age and normally higher in men than in women. NICE asks laboratories to report an eGFR above 90 as "greater than 90", because the estimate becomes less accurate as true GFR rises.

What a low result usually points to

A low eGFR usually points to the kidneys filtering less than expected, but one reading cannot say why, or for how long. MedlinePlus lists reduced blood flow to the kidneys, dehydration, heart or liver disease affecting the circulation, damage to the filters or tubules, and a blockage in the urinary tract. A short-lived drop during an illness looks the same on a single test as a lasting one.

NICE recommends confirming a new eGFR below 60 with a repeat test within two weeks. KDIGO recommends assessing urine albumin alongside GFR, using past results and repeat tests beyond three months to decide whether a change is chronic, and adding cystatin C where creatinine is likely to mislead. Below 15 is the category KDIGO calls kidney failure, which MedlinePlus describes as needing urgent medical attention. For any low result, talk to a doctor with the result in front of you.

What a high result usually points to

Above 90 the figure is loose. The equation is least accurate at the top of the range, and NICE notes that low muscle mass makes eGFR overestimate true GFR, so a very high figure can simply reflect a low creatinine from a slight build.

What moves it

Anything that moves creatinine moves eGFR, in the opposite direction.

• Muscle mass. More muscle makes eGFR underestimate true GFR, and less muscle makes it overestimate (NICE).
• A meat meal. KDIGO cites a creatinine rise of about 20 µmol/L after cooked meat or fish, which in that study meant an eGFR about 20 lower.
• Diet and supplements. KDIGO lists high-protein, ketogenic, vegetarian and low-protein diets and creatine supplements among things that make a creatinine-based eGFR less accurate.
• Medicines. Some reduce the kidneys' secretion of creatinine and lower eGFR without changing filtration (KDIGO). Others genuinely affect the kidneys, and NICE recommends checking GFR at least once a year in people on long-term anti-inflammatory painkillers, lithium or calcineurin inhibitors.
• Circumstances. NICE notes that eGFR is less reliable in acute kidney injury, pregnancy, fluid build-up, muscle wasting, malnutrition and after an amputation.

Preparing for the test

• Avoid meat in the 12 hours before the draw, as NICE advises.
• Keep the day before light, and drink water as you normally would.
• Mention creatine or protein supplements, any medicines, and pregnancy, which affects GFR. Keep taking prescribed medicines unless your doctor has told you otherwise.
• Follow the fasting instructions for the rest of the panel.

How Clare's panel handles it

eGFR is a derived biomarker in Clare's panel. The lab measures creatinine, and Clare calculates eGFR from it with your age and sex, using a validated equation. When Clare opens, members will see eGFR next to the creatinine it came from, with past results alongside.

Why it matters in the UAE

A study of 491 UAE nationals in Al Ain with, or at high risk of, cardiovascular disease, and normal filtering at the start, found that 11.4% developed an eGFR below 60 lasting three months or more over nine years, a little over 1% a year. Older age, coronary heart disease, diabetes and smoking were the independent risk factors. It was a high-risk group, not the general population.

For Ramadan, a 2020 study of people with chronic kidney disease in Al Ain found that fasting was not linked to eGFR after the month once age and starting eGFR were accounted for, though 74 people had a follow-up test.

Price

eGFR is calculated rather than sold separately, and it comes with a kidney function test. When we read public prices on 11 October 2026, a kidney function test cost from 89 to 900 at six UAE providers. Five of the six were 250 or less, and the top of the range was a specialised package. VAT was rarely stated, some figures were offer or "from" prices, and home collection can add a fee.

Related tests

eGFR is read with creatinine, the result it is calculated from; with urine protein, because guidelines assess the urine alongside GFR; and with urea (BUN) and the BUN/creatinine ratio, which help when dehydration is a possible explanation. For preparing for a full panel, see Comprehensive blood test in Dubai: what to expect.

Why the number means more over time

NIDDK notes that trends in eGFR are often more informative than a single estimate. KDIGO treats a change of more than 20% on a later test, in someone with chronic kidney disease, as worth looking into. NICE defines faster-than-expected decline as a sustained fall of 25% or more with a change of category within a year, or 15 or more a year. KDIGO recommends checking GFR at least once a year in chronic kidney disease, and NICE recommends testing adults with diabetes, high blood pressure or heart disease.

Clare is opening with a waitlist at clare.health.