New biomarker predicts kidney disease up to five years in advance

By John Murphy, MDLinx
Published November 5, 2015

Key Takeaways

A simple blood test can predict an individual’s risk for chronic kidney disease up to 5 years before kidney damage starts, according to a study published online November 5, 2015 in the New England Journal of Medicine.

Researchers found that many patients with no known kidney disease but high levels of a protein—soluble urokinase-type plasminogen activator receptor (suPAR)—went on to develop chronic kidney disease within 5 years.

“SuPAR promises to do for kidney disease what cholesterol has done for cardiovascular disease,” said the study’s senior author Jochen Reiser, MD, PhD, the Ralph C. Brown MD Professor and Chairman of Medicine at Rush University Medical Center, in Chicago, IL.

The researchers also found that in patients with already established earlier stage kidney disease, suPAR can predict decline of estimated glomerular filtration rate (eGFR).

“We can now stratify people according to their risk of developing kidney disease using suPAR levels,” said first author Salim Hayek, MD, a research fellow at the Emory Clinical Cardiovascular Research Institute, in Atlanta, GA.

In this study, the researchers measured suPAR levels and kidney function (based on eGFR rates) at baseline and again at follow up in 2,292 participants (mean age 63) from the Emory Cardiovascular Biobank. Participants were classified into four quartiles based on suPAR levels:

  • Normal suPAR: < 2,373 pg/mL
  • Above normal: 2,373-3030 pg/mL
  • High: 3,040-4,020 pg/mL
  • Very high: > 4,020 pg/mL

The researchers found that people with a higher suPAR level at baseline had a greater decline in eGFR during follow-up.

After multivariate adjustment, the researchers determined that subjects in the quartile with very high suPAR levels also had the greatest decline in eGFR rates and a very high chance—80%—of developing kidney disease in 10 years.

The researchers also used a second cohort (the Women’s Interagency HIV Study) to confirm their initial findings that high suPAR levels predict future decline of kidney function.

A powerful predictor with huge potential

Another important finding from the study is that suPAR appears to be a more powerful predictor of chronic kidney disease than other previously known high risk factors. The study findings showed that suPAR is independently associated with eGFR decline regardless of race or the presence of diabetes, for example.

Diabetes is the primary cause of chronic kidney disease, yet only about one-third of patients with diabetes develop diabetic kidney disease. “Today, nobody knows which patients with diabetes will get the disease,” Dr. Reiser said. “In our paper, we show that among patients with diabetes, the ones with elevated suPAR at baseline were more likely to develop kidney disease. This will help risk-stratify specifically patients with diabetes on their risk of future kidney disease.”

Although the test is not FDA approved, Dr. Reiser foresees that eventually—maybe sooner than later—physicians will start measuring patients’ suPAR levels on a regular basis to detect kidney risk, just as they measure cholesterol and blood pressure levels to predict heart disease.

Once physicians know which patients have high suPAR levels, he said, they can counsel them on ways to lower their risk of chronic kidney disease.

“One characteristic of suPAR is that it is modifiable to some degree by lifestyle,” Dr. Reiser said. “Also, if suPAR is high, we can be more aggressive in terms of giving medications to control high blood pressure and diabetes, which contribute to chronic kidney disease.”

If suPAR proves to be the next cholesterol test, the potential benefit to patients and the health care system is huge. Currently, more than 15% of Americans have chronic kidney disease, and approximately 4% require dialysis and/or a kidney transplant due to kidney failure. A significant decrease in the incidence of kidney disease would also dramatically cut health care spending.

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