More Muscle May Help Kidney Dialysis Patients

According to new study, for kidney dialysis patients, having more muscle improves their ability to walk and benefits their physical and mental health.

It included 105 hemodialysis patients who were assessed for body-mass index or BMI (an estimate of body fat based on height and weight), waist size, mid-thigh muscle and abdominal fat. They were also tested to see how far they could walk in six minutes and completed questionnaires to assess their physical and mental health.

Patients with a higher BMI, large waist size and more abdominal fat did worse on the walking test. Those with more mid-thigh muscle -- an indicator of higher muscle mass -- had longer six-minute walking distances and better physical and mental health scores, according to the study. It was published online April 24 in the Clinical Journal of the American Society of Nephrology.

"Because this study shows that higher muscle mass is associated with better physical function and quality of life in dialysis patients, interventions such as increased physical activity that decrease fat mass and increase muscle mass are likely to improve physical function, quality of life and survival in dialysis patients," study author Dr. Srinivasan Beddhu, of the University of Utah, said in a journal news release.

"Such interventions need to be tested in clinical trials," Beddhu added.

The study only found an association between muscle mass and improved physical function for dialysis patients. It didn't prove cause and effect.

The findings on body composition may help explain what's known as the "obesity paradox," an observation that obese dialysis patients sometimes live longer than normal-weight patients, he suggested.

"The obesity paradox has been interpreted in earlier studies as fat is good. Some have even argued that weight loss should be discouraged in dialysis patients. But the situation is more nuanced," Beddhu said.

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Severe Obesity in Teens Tied to Possible Kidney Problems

Nearly one-fifth of severely obese teens have poor kidney function, a small new study suggests.

The study included 242 severely obese teens taking part in research on weight-loss surgery.

Seventeen percent of the teens had protein in their urine, which is an early sign of kidney damage. In addition, 7 percent had indications that their kidneys were working too hard, and 3 percent showed evidence of progressive loss of kidney function, the findings revealed.

Girls were more likely than boys to have protein in their urine, while those with the highest body-mass index scores (BMI) -- an estimate of body fat based on height and weight -- and those with reduced insulin sensitivity were more likely to show signs of progressive loss of kidney function.

The study, scheduled for presentation Friday at a National Kidney Foundation meeting in Las Vegas, is believed to be the first to examine kidney function in a large group of severely obese teens.

"We plan to continue following them up after [weight-loss] surgery procedures. It will be very important to see whether their kidney function improves after surgical weight loss," study author Dr. Nianzhou Xiao, of Cincinnati Children's Hospital Medical Center, said in a kidney foundation news release.

Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

"Severe obesity is increasing and now affects 4 percent to 6 percent of U.S. children and adolescents," Dr. Beth Piraino, president of the National Kidney Foundation, said in the news release. "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," she added.

"This study indicates that kidney dysfunction is present in childhood obesity along with such complications as high blood pressure or diabetes. 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," Piraino noted.

Although the study found a connection between severe obesity and signs of kidney problems in teens, it did not establish a cause-and-effect relationship.

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