Body composition in Prader-Willi syndrome compared with nonsyndromal obesity: Relationship to physical activity and growth hormone function

Abstract

Objective: To study the relationship of fat mass, extracellular-to-intracellular-water ratio, and bone mineral density with growth hormone function and physical activity in Prader-Willi syndrome. Study design: There were 17 patients with PWS (10 women, ages 7.5-19.8 years) and 17 obese control patients, matched for gender and bone age. FM and extracellular-to-intracellular-water ratio were measured by bromide-deuterium dilution, BMD by dual-energy x-ray absorptiometry, GH function by fasted serum insulin-like growth factor-I concentration, and physical activity by doubly-labeled water in combination with basal metabolic rate by a ventilated hood. Results: The PWS group had a similar fat mass, but a lower fat-free mass, whereas the extracellular-to-intracellular-water ratio was higher compared with the control group (0.87 ± 0.07 l/l and 0.80 ± 0.06 l/l, respectively [P