Changes in body composition in male adolescents with childhood-onset GH deficiency during transition

Objective: Restarting rhGH in adolescents with childhood-onset (CO-) GHD is usually based on GH retest, IGF-1, additional pituitary hormone deficiencies, pituitary morphology and history. Short-term changes in body composition in adolescents with CO-GHD when off rhGH may contribute to the identification of those in need of treatment continuation.

Design: This is a longitudinal single-centre study.

Patients and measurements: The body composition of 90 male adolescents with low-likelihood severe GHD of adolescence was measured by DXA at the time of rhGH discontinuation and 6 months thereafter. At diagnosis, mean age was 5.4 years, height was -2.68 SDS and stimulated GH peak was 5.1 ng/mL. RhGH treatment was stopped at 16.7 years at near-final height of -0.44 SDS. The adolescents were re-examined after 3 months off rhGH using both IGF-1 and GHRH-arginine tests. Severe GHD of adolescence was defined both by stimulated GH < 16 ng/mL and by IGF-1 < -1.90 SDS.

Results: Males with severe GHD of adolescence (n = 8) gained more relative and absolute fat mass and lost significantly more relative lean body mass after 6 months off rhGH than healthy individuals (n = 82; P < 0.001). The sum of absolute fat mass gain and lean body mass loss (=body composition changes score; BCC score) correlated highly with the GH peak (R = 0.17; P < 0.001). A BCC score >7.0 kg was 88% sensitive and 94% specific for detecting severe GHD of adolescence (AUC = 0.975).

Conclusions: Short-term body composition changes when off rhGH are good clinical markers of severe GHD in male adolescents. The novel BBC score is an aggregate of these changes.