Growth hormone replacement therapy: transition from adolescence to adulthood.

Consideration of GH re-testing should be performed in all adolescents reaching the transition period (if not at start of puberty) who had been previously diagnosed with idiopathic, isolated GH deficiency. In the presence of multiple hormone deficiencies and/or clear-cut evidence of organic disease, persistence of severe GH deficiency is much more likely. Thus, GH deficiency may be "confirmed" by a low serum IGF-I concentration. During the transition period, the optimal time to reassess the integrity of the GH-IGF-I axis after prior GH treatment, the specific testing protocol to use, and the definition of GH deficiency all remain unknown. During the transition period, patients should have their GH dose lowered with (upward) adjustments made on the basis of age-and gender-adjusted serum IGF-I concentrations. GH treatment during the transition period has been shown in most, but not all, studies to be beneficial in preventing development of the features of the adult GH deficiency syndrome. It is important to remember that, during the transition period in teenagers with GH deficiency, there must be initiation of a careful plan for transfer of care to an intermist-endocrinologist with expertise in management of hypothalamic-pituitary disease in young adults.