ESPE Abstracts

Background: In children with Prader-Willi Syndrome (PWS) on Growth Hormone treatment (GHT) bone age (BA) acceleration is often observed. Little is known on reasons and consequences.

Objective and hypotheses: To quantify BA acceleration in pre-pubertal PWS children on GHT and to investigate how BA correlates with weight gain and age at onset of GHT. To assess how final height depends on pre-pubertal bone maturation, weight gain and age at onset of GHT.

Method: In 19 pre-pubertal PWS children, starting GHT (6 mg/m² per week) before age 3, longitudinal anthropometric and BA readings up to age 10 were retrospectively analyzed. In 21 adult PWS patients final height was retrospectively correlated with age at onset of GHT, pre-pubertal weight gain and bone maturation.

Results: In pre-pubertal PWS catch-up growth is completed after 2 years of GHT. Thereafter, between the age of 5 and 10 years, bone maturation was accelerated, BA velocity (years CA/years BA) amounted to 1.33 years per year. The mean increase of bone maturation of 1.6 SD between the age of 5 and 10 years exceeded the increase in height of 0.5 SD considerably. BA maturation was positively correlated with overall weight gain, but not with age at onset of GHT. In the adult group, mean final height was within the parental target height range, but significantly below mean parental target height. The earlier GHT was started, the taller they were. Final height was negatively correlated with pre-pubertal weight gain, but not with BA acceleration.

Conclusion: BA maturation exceeds growth in the pre-pubertal phase considerably without reducing final height.