ESPE Abstracts

Context: Some of the features of subjects with Prader-Willi syndrome (PWS) resemble those seen in subjects with growth hormone deficiency (GHD). Children with PWS are treated with long-term growth hormone (GH), which has substantially changed their phenotype. Currently, young adults with PWS have to stop GH treatment after attainment of adult height when they do not have adult GHD. Limited information is available about the prevalence of adult GHD in patients with PWS.

Objective: To investigate GH secretion and serum IGF-I and IGFBP-3 levels in a large group of young adults with PWS, who were GH-treated during childhood.

Methods: Cross-sectional study in 57 young adults with PWS. Main outcome measures were serum IGF-I and IGFBP-3 levels and GH peak during a combined GHRH-Arginine test. The influence of BMI, body composition and genetic subtype were assessed.

Results: Twenty-five males and 32 females with PWS participated in the current study. Mean (SD) age and adult height were 18.2 (2.1) years and −1.2 (0.9) SDS, respectively. Mean (SD) BMI SDS was 1.0 (1.3) and median (IQR) fat mass percentage (FM%) 41.5% (38.2 to 44.9). Serum IGF-I was <−2 SDS in 12% of patients and IGFBP-3 was within the normal range in all participants. Mean (SD) GH peak was 21.5 ug/l (11.7; ~ 64.5 mU/l) and below 9 ug/l in 14% of patients. Only 1 patient (2%) fulfilled the diagnostic criteria for adult GHD, also when BMI-related criteria were used. Higher BMI and FM% were significantly associated with a lower GH peak and there was no significant difference between patients with a deletion or a mUPD.

Conclusion: In a large group of previously GH-treated patients with PWS, peak GH levels during a GHRH-Arginine test were low in 14% of patients. Only 2% of patients fulfilled the criteria for adult GHD. As GH treatment has positive effects on body composition and health profile in adults with PWS, there is a need for the registration of GH treatment for adults with PWS, regardless of serum IGF-I/GH levels.