Doctors may be missing early signs of kidney disease

Chronic kidney disease is an expanding global health problem that affects an estimated 10−15 per cent of adults worldwide. By 2040, it is expected to rank among the five leading causes of years of life lost. One major challenge is the lack of widespread screening. Many patients are diagnosed only after losing more than half of their kidney function, when treatment options are limited.

Rethinking How Kidney Function Is Evaluated

To close this gap, the research team developed population-based reference charts for estimated glomerular filtration rate (eGFR), which is the most common measure used to assess kidney health. Instead of relying on a single cutoff value, the charts show how an individual's kidney function compares with others of the same age and sex. This approach is meant to help clinicians recognize elevated risk earlier and take preventive steps sooner.

"We were inspired by the growth and weight charts used in pediatrics, which intuitively help clinicians identify children at risk of obesity or undergrowth," says the first author of the study, Yuanhang Yang, postdoctoral researcher at the Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet.

Web-Based Calculator for Clinical Use

The researchers have made the eGFR distribution charts freely available to healthcare professionals and created an online calculator that shows where a patient falls within age-based population norms. The web-based calculator was developed by PhD student Antoine Creon and is intended to support clinical decision-making in routine care.

The study analyzed health data from more than 1.1 million adults in the Stockholm region of Sweden, representing about 80 per cent of residents between 40 and 100 years of age. Nearly seven million eGFR test results collected between 2006 and 2021 were used to build detailed distributions by age and sex.

Lower Percentiles Linked to Worse Outcomes

The results show that kidney function levels far from the median for a person's age and sex are associated with poorer health outcomes. Individuals whose eGFR fell below the 25th percentile faced a much higher risk of progressing to kidney failure that required dialysis or transplantation. The researchers also observed a U-shaped pattern for mortality, meaning both unusually low and unusually high eGFR percentiles were linked to an increased risk of death.

Missed Opportunities for Early Action

The findings also highlight gaps in current clinical practice. Among people with an eGFR above 60 ml/min/1.73 m² but still below the 25th percentile for their age, only one fourth had undergone additional testing for urinary albumin. This test is important for identifying early kidney damage and guiding timely intervention.

"For example, consider a 55-year-old woman with an eGFR of 80. Most clinicians would not react to such a seemingly normal value. However, our charts show that this corresponds to the 10th percentile for women of that age, and that she has a three-fold higher risk of starting dialysis in the future. This signals an opportunity to act earlier," says Juan Jesús Carrero, professor at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.

Study Background and Funding

The research is part of the SCREAM project and received funding from the Swedish Research Council, the Swedish Heart-Lung Foundation, Region Stockholm, and the Swedish Kidney Foundation, among others. The researchers report no conflicts of interest related to the content of the study.