- Kidney function tests in the normal range can still signal risk if low for age and sex
- A Swedish study analyzed over 1.1 million adults using age- and sex-specific eGFR charts
- Adults below the 25th percentile for eGFR faced higher risk of serious kidney disease later
Have you ever heard your doctor say your kidney test results are "normal"? That's usually means everything is under control. But what if "normal" isn't always as reassuring as it sounds? A recent study published in the journal Kidney International suggests that even kidney function results that fall within the standard normal range might conceal early signs of serious disease, particularly when those results are unusually low for your age, not just compared to the average adult. Here is all about what the study found and what this may mean for you.
What he Study Found
Researchers from Sweden's Karolinska Institute looked at more than 1.1 million adults in the Stockholm region. The study analysed nearly seven million estimated glomerular filtration rate (eGFR) tests , which is the number doctors typically use to gauge how well your kidneys are filtering blood. The research realised something intriguing. You can have an eGFR value that sits within what's generally considered "normal," but if it's low for your age and sex, it might still signal a higher risk of future kidney problems.
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Anyone who's ever talked about health markers with a clinician knows that "normal ranges" tend to be broad. They don't always consider the nuances of age or biological variation. But the researchers in this study took a clever approach: they created age- and sex-specific charts much like how we track children's weight or height against age-based percentiles, so that 55-year-old's kidneys aren't unfairly compared with those of a 25-year-old.
The basic crux of the story is what counts as "normal" for someone in their twenties might not be what is truly healthy for someone in their fifties or sixties.
Why These Findings Matter For You
Here's where things get interesting. The study showed that adults whose eGFR fell below the 25th percentile for their age and sex even though still within the normal lab range were significantly more likely to end up with serious kidney disease in the future. Some even faced a much higher risk of progressing end-stage kidney failure, requiring dialysis or a transplant.
A Real-World Example
Imagine you're 55 and your eGFR is 80. Most clinicians would read that comfortably in the "normal" zone. But the age-specific charts show that for someone of your age and sex, this sits around the 10th percentile meaning 90 per cent of people your age have higher kidney function. According to the study, someone in this position could have nearly a three-fold greater risk of progressing to serious kidney disease compared with peers whose eGFR sits nearer the median. That's the sort of risk doctors might miss if they only look at broad "normal" ranges.
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A Tool That Could Change Clinical Practice
Researchers created an age-adjusted eGFR charts and a free online calculator to help doctors compare a patient's kidney function with others of the same age and sex. However, the study found a problem; many people with eGFR above 60 but still low for their age did not get follow-up urine tests for albumin, an early sign of kidney damage. As a result, some at-risk patients missed important checks that could lead to early treatment or lifestyle changes.
Why Early Detection Really Matters
Chronic kidney disease is sneaky. Early stages rarely cause symptoms, and many don't get diagnosed until more than half of kidney function is lost. Worldwide, it's a growing problem, affecting roughly 10-15 per cent of adults and expected to become one of the top causes of years of life lost by 2040.
By thinking more carefully about what "normal" really means for different people, clinicians might be able to catch risk much earlier. It's a bit like spotting heart disease risk before a heart attack or identifying pre-diabetes before blood sugar skyrockets early action can make all the difference.
If your routine kidney tests come back "normal," that's still good news but it might not tell the whole story. According to this new research, even those normal results might warrant a second look if they're lower than expected for your age and sex. Thankfully, tools are now emerging to help doctors interpret these nuances better, which could give patients a real chance at preventing serious disease down the line.
Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.
