Almost 18% of severely obese adolescents show signs of abnormal kidney function, according to new research presented at the National Kidney Foundation's 2014 Spring Clinical Meetings.
The presence of too much albumin - a type of protein - in the urine, known medically as albuminuria or proteinuria, is an early sign of kidney damage. Doctors also use a test called glomerular filtration rate (GFR) to estimate how quickly filtered fluid flows through the kidneys. A GFR of 90 or over indicates normal kidney function, while GFR less than 90 indicate a progressive loss of kidney function. A GFR that's too high, which is common among obese children and adults, indicates hyperfiltration, meaning the kidneys are working extra hard. Having hyperfiltration for a long period of time can lead to leakage of protein into the urine.
Among 242 adolescents enrolled in the Teen-Longitudinal Assessment of Bariatric Surgery study , 17 percent had protein in their urine, 3 percent had abnormally low GFR (less than 60), and 7 percent had abnormally high GFR (more than 150), Dr. Nianzhou Xiao of Cincinnati Children's Hospital Medical Center and colleagues found.
Teens with a higher body mass index, as well as those with less sensitivity to the blood-sugar-regulating hormone insulin, were more likely to have abnormally low GFR. Females were more likely than males to have protein in their urine.
"This study represents the first attempt to characterize kidney function status in a large cohort of severely obese adolescents," Dr. Xiao said. "We plan to continue following them up after bariatric surgery procedures. It will be very important to see whether their kidney function improves after surgical weight loss."
"Severe obesity is increasing and now affects 4-6% of U.S. children and adolescents. If untreated, obesity during adolescence is associated with a higher prevalence of chronic kidney disease and other serious conditions in adulthood, making obesity a huge public health burden. Pediatricians should counsel obese children and their family proactively about the health concerns linked to obesity and the importance of weight loss for patients who are obese," said Beth Piraino, MD, President of the National Kidney Foundation.
"This study indicates that kidney dysfunction is present in childhood obesity along with such complications as high blood pressure or diabetes," continued Piraino. "Lifestyle changes such as increased physical activity and healthy eating are critical to improving the overall health of the American population and need to start with our youth. The National Kidney Foundation has developed a number of educational initiatives to promote healthy lifestyle and protect the kidneys."