ESPE Abstracts

Background: Restarting rhGH treatment in adolescents with childhood-onset GH deficiency (CO-GHD) is usually based on the GH re-test, IGF-1, additional pituitary hormone deficiencies and pituitary gland morphology, but not on body composition. Short-term changes of body composition in adolescents with CO-GHD when off rhGH may contribute to the identification of those in need of continuation of treatment.

Study design: In this prospective single-centre study the body composition of 58 adolescents (12 females) with CO-GHD and low-likelihood GHD of adolescence was measured by DXA 6 months before and at rhGH stop as well as 6 and 12 months thereafter. At diagnosis mean age had been 5.4 y, height -2.85 SDS and stimulated GH peak 5.0 ng/ml. Treatment with rhGH was stopped at 16.4 y at near-final height of −0.48 SDS (target height −0.45 SDS). The adolescents were re-examined after 3 months off rhGH using serum IGF-1 and GHRH-arginine test. GHD of adolescence was defined by stimulated GH <16 ng/ml and IGF-1 <−1.9 SDS.

Results: In males, those with GHD of adolescence (n=5) gained significantly more relative and absolute fat mass and lost significantly more relative lean body mass during the first six months off rhGH than the healthy individuals (n=41) (P<0.005). These changes were non-significant in females with GHD of adolescence (n=4) (P>0.4). During the first six months off rhGH the sum of absolute fat mass gain und lean body mass loss (kg) correlated highly with the GH peak of the re-test in males (R=0.54; P<0.001), but not in females (R=0.004; P=0.88).

Conclusions: Short term changes of body composition when off rhGH are good clinical markers of GHD in male adolescents, but not in females. Physiological differences in muscle mass, fat mass and testosterone levels may cause these sex differences.