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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #109021
Title: BODY COMPOSITION ABNORMALITIES IN CHILDREN WITH PRADER-WILLI SYNDROME: AGE DEPENDENCY AND LONG-TERM EFFECTS OF GROWTH HORMONE THERAPY

Author
item EIHOLZER, URS - FOUNDATION GROWTH PUBERTY
item L'ALLEMAND, DAGMAR - FOUNDATION GROWTH PUBERTY
item VAN DER SLUIS, INGE - UNIV HOSP., ROTTERDAM
item STEINERT, HANS - UNIVERSITY OF ZURICH
item GASSER, THEO - UNIVERSITY OF ZURICH
item Ellis, Kenneth

Submitted to: Hormone Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2000
Publication Date: 10/23/2000
Citation: N/A

Interpretive Summary: Obesity is a growing epidemic worldwide. Prader-Willi syndrome is a genetic type of obesity which can be used as a model to study some of the causes and contributing factors to the general problem. Features of this syndrome include short stature, obesity (which emerges around prepuberty, after a period of underweight) and poor muscle tone. It is thought that a growth hormone deficiency may account for short stature, increased fat mass and decreased lean body mass. We wanted to find out specifically whether fat mass is reduced in the long term in Prader-Willi patients by growth hormone therapy. We also were curious as to whether this therapy would counteract the patients' lean tissue mass deficit over the long term. We studied 16 children with this syndrome at different ages: when they were young and underweight, when they were prepubertal and overweight, and when they were pubertal and overweight. We gave them growth hormone for about 3.5 years. During this time we measured their body composition and evaluated fat and lean mass. The percentage of fat decreased during this period, although the underweight young children incurred an increase in the percentage of fat to a normal-weight range. Also, we noted that the height of the young underweight and prepubertal overweight children markedly improved. But we found that growth hormone alone was not enough to increase lean body mass in the long term, in the dosage we administered. After 2 years of therapy, there seems to be a loss of sensitivity to the metabolic, but not the growth-promoting effects of this hormone. These findings contribute quite valuable information to our pool of knowledge about obesity, age-related influences, and treatments.

Technical Abstract: Obesity and hypothalamic growth hormone deficiency contribute in different ways to the disturbances of body composition in PWS; while both increase the fat compartment, the reduction of lean tissue mass has been attributed mainly to growth hormone deficiency. Therefore, body composition measured by DEXA was prospectively studied in 16 children with PWS under treatment with hGH (0.037mg/kg/d) during 3.5 years on average. In the long term, there is a net reduction of body fat in the prepubertal overweight children (from 3.1 to 1.1 SD), as well as in the pubertal ones, with a minimum at the end of the second year of treatment. In the young, initially underweight children with PWS, fat mass increases in spite of GH therapy, but remains in the normal range. Weight for height (WfH) correctly reflects body fat mass and its changes. The initial deficit of lean mass (-1.8 SD in prepubertal overweight children) is counteracted by GH only during the first year of therapy (increase to -1.33 SD). But in the long term, GH therapy does not further compensate for this deficit, when lean mass is corrected for its growth-related increase. In conclusion, exogenous GH dramatically changes the phenotype of PWS in childhood: height and fat mass become normal, but GH, at least in the dosage administered, is not sufficient to normalise lean tissue mass.