Prader-Willi syndrome (PWS) is a chromosomal disorder and growth failure is a common presentation. Growth hormone (GH) treatment is beneficial in PWS although the optimal age for starting GH is unknown. We investigated whether GH response in PWS was associated with the age of GH commencement by comparing 16 children who commenced GH before 3 years of age (early group) with 40 children who commenced GH after 3 years of age (late group) from the Ozgrow database. Height SDS, body mass index (BMI) SDS, bone age (BA)-chronological age (CA) ratio, change in height (Δ Ht) SDS and change in BMI during 4 years of GH treatment were compared between the groups. The early group had better height SDS and Δ Ht SDS. BA delay was more pronounced in the early group but BA did not mature beyond CA with GH therapy in either group. Although the initial GH dose for the early group was lower than that of the late group, the former had better height outcome. The starting GH dose seen in the database is lower than the dose used by international centres.

Recombinant human growth hormone (rhGH) therapy in Prader-Willi syndrome (PWS) causes increased basal metabolic rate and oxygen consumption, and hence increased ventilatory load. The case of an adolescent with PWS who experienced respiratory deterioration with an increase in rhGH and improvement with cessation of therapy is reported. P rader-Willi syndrome can result from a functional deletion of the paternally imprinted region at 15q11-13. It usually presents in infancy with marked hypotonia and poor feeding, in contrast to the middle childhood years when hyperphagia and obesity develop. Disturbed hypothalamic function is often associated with hypogonadism, short stature, lowered basal metabolic rate (BMR), and blunted growth hormone secretion in response to provocation testing; thus rhGH is often prescribed.

Anterior hypothalamic deafferentation and infusion of human GH (hGH) in the normal male rat caused a marked reduction in the hepatic concentration of alpha 2u-globulin, an androgen-dependent protein. Although s.c. injections of hGH (twice-daily) resulted in more than a 50% reduction in the hepatic level of alpha 2u-globulin, the same dose of hGH when administered continuously through osmotic minipumps caused a threefold greater inhibition. The decreased hepatic concentration of alpha 2u-globulin after hGH administration was associated with corresponding changes in the hepatic level of translatable alpha 2u-globulin messenger RNA. Continuous infusion of hGH through osmotic minipumps and removal of the anterior hypothalamic influence on GH secretion by deafferentation also caused a marked reduction in the cytoplasmic androgen-binding activity of the rat liver. These results suggest that alterations in the level and pattern of GH secretion may influence hepatic androgen-binding activity and alpha 2u-globulin synthesis.

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