Lack of reduction in body fat after treatment with insulin-like growth factor-I in two children with growth hormone gene deletions

Two patients with growth hormone (GH) gene deletions were treated with reco mbinant insulin-like growth factor-I (IGF-I) (80-240 (mu g/kg/ day) and the effects on bone mass and body composition were compared to administration of GH (0.075 U/kg/day) to 8 patients with idiopathic GH deficiency. Bone ma ss and body composition were measured by dual photon X-ray absorptiometry ( DD(A) before and 3 and 6 months after treatment with GH or IGF-I. Similar i ncreases in growth velocities were observed after GH and IGF-I treatment. T reatment with GH resulted in prompt and significant reduction in body fat p ercentage (basal, 3 and 6 months: 22+/-10, 17+/-9, and 16+/-9%) where-as bo dy fat percentage remained unchanged after IGF-I therapy (basal, 3 and 6 mo nths: 49, 52 and 48% in patient 1 and 45, 42 and 43% in patient 2, respecti vely). Fat percentage remained elevated after 18 months of IGF-I treatment in patients 1 (51%) and 2 (44%), respectively. Lean mass and bone mineral c ontent increased with GH and IGF-I therapies. We conclude that reduction of body fat measured by DEXA, observed after administration of GH but not aft er IGF-I treatment in these children with GH deficiency, suggests that the GH effect on body fat mass is not mediated by circulating IGF-I. (C) 2000, Editrice Kurtis.