Published June 2015

Even after undergoing bariatric surgery to control severe obesity, adolescents continue to show underlying, subclinical biomarkers of kidney disease.

A research team led by Mark Mitsnefes, MD, MS, director of the Clinical and Translational Research Center, studied 28 patients under age 20 who had undergone bariatric surgery for severe obesity. Their findings were published in June 2015 in Obesity.

The team measured baseline urine levels of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), and interleukin-18 (IL-18), three biomarkers previously linked to early structural and inflammatory kidney injury. Levels were measured at baseline, and 6 and 12 months after surgery, and compared against 44 age and sex-matched control subjects.

The team expected to find a decline in signs of kidney disease that corresponded a decline in weight. However, despite weight losses as high as 30 percent, biomarkers remained high enough to indicate continuous kidney injury.

These findings raise questions for clinicians working to prevent childhood obesity from leading to chronic kidney disease in adulthood, Mitsnefes says. Are these biomarkers reversible? How much kidney injury risk do children who undergo bariatric surgery still face as adults?

“We can’t answer these questions unless we follow these patients for many more years,” Mitsnefes says. “However, our initial findings of persistently elevated biomarkers of kidney injury, despite weight loss, warrant long-term follow-up of kidney status in these adolescents.”