Growth hormone retesting during puberty: a cohort study.

Objectives: To report the frequency and characteristics of growth hormone (GH) deficiency (GHD) in adolescents who had normalized GH secretion at mid-puberty and to identify possible factors predictive for GH sufficiency at puberty.

Design: Clinical analysis of children affected by GHD at five time points: diagnosis; first year of therapy; intermediate stage of puberty; retesting and end of growth phase.

Methods: The study population was 80 children with idiopathic GHD and treated with GH for at least 2 years. Treatment was discontinued at the intermediate stage of puberty. Retesting with an arginine test was performed 12 weeks later. If GH peak at retesting was ≥8 μg/L, the therapy was definitively discontinued, otherwise it was restarted and continued until achievement of near-final height.

Results: GH therapy was discontinued in 44 children (55%), and restarted in 36 (45%). No evidence of differences in definitive height and in the delta height between the genetic target and the definitive height was found between the two groups. The only predictive factor for GHD at mid-puberty was the insulin growth factor-1 (IGF-1) level at 1 year of GH treatment.

Conclusions: GH secretion should be retested at mid-puberty. Retesting at puberty may reduce potential side effects and minimize costs, without impairing growth potential and final height.