You go in for a regular blood draw, the result arrives a few days later with "eGFR" and a number next to it, and nobody explains what it should look like for someone your age.
About 37 million American adults have chronic kidney disease, and roughly 90 percent of them do not know it, according to the National Kidney Foundation.
One big reason is that eGFR drops gradually with age. A value that looks worrying at 40 may be entirely normal at 75.
eGFR, short for estimated glomerular filtration rate, shows how well your kidneys are filtering. It is calculated from a simple blood test that measures creatinine, a waste product the kidneys clear from the body.
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What a normal eGFR looks like by age
The National Kidney Foundation publishes the following averages for healthy adults without kidney disease.
They are not strict cutoffs. They show where most people of a given age tend to land.
Age (years) | Average eGFR Also read: New global study reveals why stroke is affecting millions of younger people |
|---|---|
20 to 29 | 116 |
30 to 39 | 107 Also read: Want to know how healthy your heart is? This fitness measure could help |
40 to 49 | 99 |
50 to 59 | 93 Also read: Measles is making a comeback in America: This could be the reason |
60 to 69 | 85 |
70 and above | 75 Also read: Scientists reveal how fast you need to walk to get a real workout |
The foundation notes that eGFR declines with age even in people without kidney disease. An eGFR of 85 is typical in a 65-year-old. The same number in a 35-year-old would raise questions.
The five stages of kidney disease
Doctors sort kidney health into five stages based on eGFR. The lower the number, the less filtering the kidneys are doing.
Stage | What it means | eGFR |
|---|---|---|
1 | Normal function, possible early damage | 90 or above |
2 | Mild loss of function | 60 to 89 |
3a | Mild to moderate loss | 45 to 59 |
3b | Moderate to severe loss | 30 to 44 |
4 | Severe loss | 15 to 29 |
5 | Kidney failure | Below 15 |
One low reading does not make a diagnosis. According to the American Kidney Fund, an eGFR that stays below 60 for three months or more is what signals kidney disease.
That is also the point where many doctors recommend a referral to a nephrologist, a kidney specialist.
What pushes kidney function down?
The two biggest drivers of kidney decline in adults are diabetes and high blood pressure.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, high blood sugar damages the small filters in the kidney. High blood pressure wears down the blood vessels that run through them.
Everyday painkillers add to the picture. The NIDDK warns that regular use of nonsteroidal anti-inflammatory drugs, such as ibuprofen and naproxen, can damage the kidneys.
Early kidney disease usually has no symptoms. Testing is the only way to know how well the kidneys are working. That is why people with diabetes, high blood pressure, heart disease or a family history of kidney failure are told to get checked.
How to protect kidney function over time
The advice is familiar, which is why it gets ignored. The NIDDK recommends keeping blood pressure and blood sugar at the target your doctor sets.
It also calls for being active at least 30 minutes most days, aiming for seven to eight hours of sleep a night, and keeping sodium below 2,300 milligrams a day.
Painkillers are the quieter risk. An occasional ibuprofen for a headache is not the issue. Daily or near-daily use over months and years is where kidney damage builds up.
If your eGFR comes back below 60 and stays below 60 on a repeat test three months later, ask your doctor whether a referral to a nephrologist is appropriate.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.