Effectiveness, economical and safety aspects of growth hormone (GH) therapy in growth promoting doses in patients with isolated GH deficiency after the attainment of near-final height. Is there a need to modify the criteria of therapy withdrawal?

INTRODUCTION: Apart from growth promotion, growth hormone (GH) has important metabolic effects. Patients with severe GH deficiency (GHD) should be treated with GH throughout life. Current criteria for growth promoting therapy withdrawal in Poland differ from the latest recommendations. AIM OF THE STUDY: To assess cost-effectiveness and safety of continuation of GH therapy in growth promoting doses in patients with isolated GHD after the attainment of near-final height (near-FH) and the incidence of persistent GHD after the therapy withdrawal. MATERIAL AND METHODS: 160 children with isolated GHD (height < 3 centile, GH peak < 10.0 µg/l), who continued GH therapy for growth promotion after the attainment of near-FH (height velocity < 2.5 cm/year, bone age ≥ 16 years in boys, ≥ 14 years in girls). Clinical endpoints were: absolute height gain after near-FH, GH dose – cumulative and recalculated for additional 1.0 cm of height, number of injections, incidence of increased IGF-1 concentrations (IGF-1 SDS > 2.0) at near-FH and incidence of severe GHD in retesting (performed in 62 patients). RESULTS: Height gain after near-FH was 1.1 ±0.8 cm in boys and 1.0 ±0.8 in girls. Increase of height by 1.0 cm required on average 487 mg of GH (264 injections). IGF-1 concentrations at near-FH were increased in 39 patients, with no clinical side effects. None of the patients retested had GH peak < 3.0 µg/l, while 37 (60%) had GH peak > 10.0 µg/l. CONCLUSIONS: There is no rationale to continue GH therapy in growth promoting doses in the patients with isolated GHD after fulfilling the criteria of near-FH.