New paradigms for growth hormone therapy in children

Abstract

Much has been learned over the last two decades regarding the management of growth hormone (GH) deficiency (GHD) in children and adolescents. However, significant divergence and debate continue to exist on the ideal approach to the management of GHD. Despite active controversy, several paradigms have recently emerged which should guide the treatment of GHD patients as we head into the new millennium. The primary objectives of GH therapy remain the normalization of height in childhood and the attainment of normal adult height, but the recognition of the metabolic roles of GH define additional therapeutic benefits. A daily subcutaneous injection of recombinant human GH in a dose range of 25-50 microg/kg/day has been established as the mainstay of therapy. Alternative modes of treatment including GH-releasing hormone (GHRH), GH secretagogues and depot GH have been developed, but evaluation of their clinical utility remains incomplete. Careful monitoring and follow-up of pediatric GHD patients by a pediatric endocrinologist are essential. Accurate determination of height velocity and interval height increases (expressed as the change in height z score) continue to be the most important parameters in monitoring the response to treatment. Monitoring serum insulin-like growth factor (IGF)-I and IGF-binding protein-3 has gained utility in the assurance of compliance and safety, but does not always correlate well with the growth response. A clear role for a biochemical as well as an auxological monitoring approach has nonetheless been established. The comparison of attained growth response to that which has been calculated by various modeling approaches is also becoming a valuable monitoring tool. Significant side effects of GH therapy are quite rare and are easily identified and addressed during close follow-up. Despite previous concerns, it now appears that in the absence of additional risk factors there is no evidence that long-term recipients of GH are at any increased risk of developing diabetes, slipped capital femoral epiphysis, brain tumor recurrence or leukemia. Although GHD may or may not persist into adult life, adult GHD diagnostic criteria and the importance of GH therapy in adult GHD patients have recently been established. Therefore, the pediatric endocrinologist now has a crucial role in guiding the transition to adult GHD management in collaboration with the adult endocrinologist. In the years to come, with the continued investigation and collaborationof experts from around the world, the approach to GH treatment will undoubtedly continue to evolve and improve.