Researchers have shown that declines in kidney function are detectable long before the emergence of other obesity-related diseases such as diabetes and high blood pressure.
First author Vanessa Grubbs, MD, UCSF assistant adjunct professor of medicine, and senior author Kirsten Bibbins-Domingo, PhD, MD, professor of medicine, led a team that analyzed 10 years' worth of health data from CARDIA (Coronary Artery Risk Development in Young Adults), a national multi-center research project that has tracked the health of thousands of black and white young adults since its beginnings in 1985.
The 2,891 CARDIA participants included in the study were categorized according to four ranges of body mass index (BMI): normal weight, overweight, obese, and extremely obese.
At the beginning of the time period studied, the patients averaged 35 years of age and all had normal kidney function in the normal range, though higher-BMI patients were at the lower end of that range.
Kidney function diminished over time in all participants, but the decline was significantly greater and more rapid in heavier patients, and appeared to stem exclusively from BMI.
Grubbs said that when they accounted for diabetes, high blood pressure, and inflammatory processes, the body mass index was still a predictor of kidney function decline, so there was something unique about just being too large that in and of itself affected kidney function even before the onset of frank kidney disease.
The new study has been published online in the American Journal of Kidney Diseases.
