Growth hormone improves body composition, fat utilization, physical strength and agility, and growth in Prader-Willi syndrome: A controlled study

Background: Obesity and hypotonia in children with Prader-Willi syndrome (P WS) are accompanied by abnormal body composition and diminished energy expe nditure resembling a growth hormone-deficient state. Hypothalamic dysfuncti on in PWS often includes decreased growth hormone (GH) secretion, suggestin g a possible therapeutic role for exogenous GH treatment. Objectives and methods: After 6 months of observation to determine baseline growth rate, and with the use of a 12-month randomized controlled study de sign, the effects of GH treatment (1 mg/m(2)/d) on growth, body composition , strength and agility, pulmonary function, resting energy expenditure (REE ), and fat utilization were assessed in 54 children with PWS (n = 35 treatm ent and n = 19 control). Percent body fat and bone mineral density were mea sured by dual x-ray absorptiometry. Indirect calorimetry was used to determ ine REE and to calculate respiratory quotients. Results: Stimulated levels of CH in response to clonidine testing were low in all patients (peak, 2.0 ng/mL). After 12 months, CH-treated subjects sho wed significantly increased height velocity Z scores (mean, -1.0 +/- 1.7 to 4.6 +/- 2.9; P < .001), decreased percent body fat (mean, 46.3% +/- 8.4% t o 38.3% +/- 10.7%; P < .001), and improved respiratory muscle function, phy sical strength, and agility (sit-ups, weight-lifts, running speed, and coor dination). A significant decline in respiratory quotients occurred during G H therapy (0.81 to 0.77 P < .001), but total REE did not change. Conclusions: CH treatment of children with PWS accelerated growth, decrease d percent body fat, and increased fat oxidation but did not significantly i ncrease total REE. Improvements in respiratory muscle strength, physical st rength, and agility also occurred, suggesting that GH treatment may have va lue in reducing some physical disabilities experienced by children with PWS .