If you had a routine blood test in the past few years, chances are your results already include a three-digit number labeled eGFR.
Most patients scroll past it. Few know what it is, and even fewer know what a "normal" reading looks like for their age.
The estimated glomerular filtration rate is a calculated measure of how efficiently your kidneys filter waste from your blood. It is derived from a creatinine reading combined with your age and sex, and the American Kidney Fund describes it as a measure of how well your kidneys are working.
The number matters because kidney disease is common and often silent. The National Kidney Foundation estimates that about 35.5 million US adults have kidney disease, and roughly 9 in 10 do not know they have it.
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Where the 60 threshold comes from
Both the American Kidney Fund and the National Institute of Diabetes and Digestive and Kidney Diseases treat 60 as the general cutoff for adult kidneys.
NIDDK states that a GFR of 60 or more is in the normal range, while a result of 15 or less is called kidney failure.
A reading below 60 that persists for three months or more is the classic warning sign for chronic kidney disease. That is the trigger for a follow-up conversation with your doctor.
Age changes the number, even in healthy kidneys
Here is the part patients rarely hear. Kidney filtration slows with age, and average eGFR values drift downward decade by decade even in people without kidney disease.
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According to the National Kidney Foundation, the typical eGFR for a healthy 25-year-old sits around 116, while someone in their 70s averages around 75. So a reading of 65 at age 40 is a very different clinical picture than 65 at age 80.
Age (years) | Average eGFR |
|---|---|
20-29 Also read: Your Long COVID may be quietly raising your heart and kidney risk | 116 |
30-39 | 107 |
40-49 Also read: 8 warning signs of low blood pressure and when it becomes dangerous | 99 |
50-59 | 93 |
60-69 Also read: Creatinine levels by age and sex: what your blood test number means | 85 |
70+ | 75 |
The stage chart, in plain language
Kidney specialists use the eGFR number to sort function into five stages. Here is what the ranges typically mean, drawn from the National Kidney Foundation and the American Kidney Fund.
eGFR | Stage | What it means |
|---|---|---|
90 or higher | 1 | Normal kidney function |
60-89 | 2 | Mildly reduced, monitor but usually not disease |
45-59 | 3a | Mild-to-moderate loss |
30-44 | 3b | Moderate-to-severe loss |
15-29 | 4 | Severe loss |
Under 15 | 5 | Kidney failure, dialysis or transplant territory |
When a normal number is not the whole picture
A single reading has limits. The American Kidney Fund cautions that the eGFR may not be accurate if you are younger than 18, pregnant, very overweight or very muscular, because the underlying creatinine value can be skewed.
Kidney disease can also be present even with a normal eGFR when there is protein in the urine or physical damage to the kidney.
Recent research has echoed that warning, showing that a "normal" kidney test can still hide a substantially raised dialysis risk in some patients.
That is why doctors typically look at the trend across multiple tests, not just one snapshot, and often pair the blood test with a urine check for albumin, a protein that should not spill into urine when kidneys are working normally.
What to actually do with your number
The practical step is straightforward. Pull up your last few lab reports and note your eGFR values. If any reading is below 60, or if the trend is falling faster than the roughly one-point-per-year decline expected with age, ask your primary care doctor whether a repeat test in three months is appropriate.
That is the follow-up window the National Kidney Foundation flags for a persistent result below 60, the threshold that defines chronic kidney disease.
This article is made and published by Mie Hermansen, who may have used AI in the preparation.