Objective: The aim was to investigate whether, in the absence of gonads, GH could bring forward the age of neuroendocrine activation resulting in onset of puberty.
Design: In girls with Turner's syndrome, we evaluated the effects of GH therapy on developmental changes in FSH serum concentrations used as an indicator of neuroendocrine maturation in the absence of gonads.
Patients: Thirty-nine girls with Turner's syndrome aged 4.0-17.1 years were treated using GH (25 IU/m2 week) for 1 year.
Measurements: Serum levels of FSH and IGF-I were measured before initiation of GH therapy and 12 months later, after interruption of GH treatment for 2 days.
Results: Pretreatment FSH levels were low between 6 and 10 years and increased markedly at 10-11 years of age. This pattern was unchanged after 1 year of GH therapy. Pretreatment IGF-I levels were positively correlated with age and they were uniformly increased after 1 year of GH therapy.
Conclusions: Our data suggest that GH and its effector, IGF-I, do not influence the timing of the onset of puberty through an effect on its neuroendocrine control.