LOW-DOSE RECOMBINANT HUMAN GROWTH-HORMONE NORMALIZES BONE METABOLISM AND CORTICAL BONE-DENSITY AND IMPROVES TRABECULAR BONE-DENSITY IN GROWTH-HORMONE DEFICIENT ADULTS WITHOUT CAUSING ADVERSE-EFFECTS

OBJECTIVES Prolonged GH deficiency induces alterations in bone metabol ism and structure. Trials in GH deficient adults (GHDA) employing high dose GH replacement therapy produced conflicting results, and caused several adverse effects. This prompted us to study the effects of rhGH treatment on bone metabolism and structure at lowest doses so far use d. DESIGN Nine GHDA (7 males and 2 females, aged 25-34 years) were stu died before, after 12 months of rhGH treatment (70 mu g/kg/week, divid ed into 3 injections, administered s.c. at 2000 h on Monday, Wednesday and Friday, respectively) and after 12 months off therapy. MEASUREMEN TS Serum IGF-I, IGFBP-3, bone-gla-protein (BGP), procollagen-III (PIII NP), PTH and vitamin D, and bone mineral density (BMD) at proximal (Pr ox) and ultradistal (Dist) sites of the radius were measured. RESULTS Before treatment, IGF-I, IGFBP-3, BGP and PIIINP levels, as well as bo th Prox and Dist BMD, were significantly lower than in controls. GH th erapy normalized all these parameters, except for the Dist value, whic h nonetheless increased. No significant changes in PTH and vitamin D v ariation were seen. After 12 months off therapy all parameters returne d to pretreatment levels. CONCLUSIONS Our results suggest that 12 mont hs of rhGH treatment at the lowest doses so far used normalizes bone m etabolism and cortical bone density, and improves trabecular bone dens ity without causing adverse events.