Therapy for 6.5-7.5 years with recombinant insulin-like growth factor I in children with growth hormone insensitivity syndrome: a clinical research center study.

Eight children with GH insensitivity syndrome were treated with recombinant human insulin-like growth factor I (IGF-I) (80--120 microg/kg sc twice daily) for 6.5--7.5 yr. We previously reported that height velocity (HV) improved with treatment (from mean pretreatment HV of 4.0 cm/yr), to 9.3 cm/yr for the first year and 6.2 cm/yr for the second year. HV remained slightly below this during the subsequent years (mean HV: 5.4, 5.5, 5.2, and 4.8 cm/yr during years 3--6). Mean height SD score before therapy was -5.6; and it improved to -4.5, -4.4, and -4.2 after 2, 4, and 6 yr of therapy, respectively. Treatment was accompanied by gain in body weight and fat. Bone age advanced normally in the prepubertal patients, but it advanced more rapidly during the latter years of treatment in those patients undergoing pubertal changes. The growth of spleen and kidneys (determined by ultrasound) was rapid in the first 2--3 yr of therapy. More age- appropriate growth ensued, but six patients had a renal length for height more than 2 SD above the mean at 6--7 yr of treatment. No major adverse changes in biochemical profile were observed. IGF-I-related hypoglycemia occurred early in treatment with the younger patients, but this problem abated as treatment was continued. IGF-I therapy is effective in promoting statural growth in GH insensitivity syndrome patients, but the growth response is neither as intense nor as well-sustained as the growth response to GH among children with GH deficiency.