Monitoring and optimising of growth hormone (GH) therapy in GH-deficient children - the role of assessment of insulin-like growth factor-I (IGF-I) secretion and IGF-I/IGF binding protein-3 molar ratio

Introduction: Increase of IGF-I secretion is the main hormonal indicator of growth hormone (GH) therapy effectiveness but elevated IGF-I concentration connected with low IGFBP-3 may be associated with an increased risk of malignancy. The aim of the study was optimisation of GH therapy in children with GH deficiency (GHD) under the control of height velocity, IGF-I secretion and IGF-I/IGFBP-3 molar ratio. Material and Methods: The analysis comprised 81 children (60 boys, 21 girls), with GHD, who were treated for two years with GH doses modified yearly to maintain normal serum IGF-I concentration. The diagnosis of GHD was based on decreased GH secretion in 2 standard stimulating tests. The dose of GH was increased if either IGF concentration remained decreased (i.e. IGF-I SDS was below –2.0 after a year of treatment) or patient's height velocity (HV) in1 st year of GH administration was below 8 cm/year. Results: In most of patients significant increase of IGF-ISDS and IGF-I/IGFBP-3 molar ratio, together with improved HV, was observed during GH therapy. In 6 patients with low IGF-I after 1 year of therapy, the increase of GH dose led to slight increase of IGF-I concentration and improved HV vs. children with unchanged GH dose. In 15 patients with slow HV in 1st year of therapy, there was no improvement of HV despite increased GH dosage. In 4 patients IGF-I SDS after 1 year of GH therapy in standard doses was elevated, the decrease of GH dose caused normalisation of IGF-I concentration but connected with decreased HV. Conclusions: Monitoring of IGF-I and IGFBP-3 concentrations and individualising of GH doses during the therapy in children with GHD seems to be necessary for optimising the therapy. (Clin. Exp. Med. Lett. 2006; 47(4):219-223)

Keywords: growth hormone deficiency, growthhormonetherapy, insulin-likegrowthfactor-I, insulin-likegrowthinsulin-likegrowth factor binding protein-3, height velocity