IGF binding protein 3 in patients with Laron type dwarfism: effect of exogenous rIGF‐I

Abstract

Objective The aim of the study was to investigate the serum levels of IGFBP‐3, the major IGF‐I binding protein, in patients with Laron type dwarfism (LTD) before and after IGF‐I treatment design and patients Eight Laron type dwarfism patients (four children and four adults) were treated for 7 days by one daily s.c. injection of blosynthetic IGF‐I In doses of 120 or 150 μ g/kg/day. measurements Blood was sampled in the fasting state before and 1 and 7 days after the last Injection results It was found that IGF‐I administration significantly reduced plasma hGH levels with recovery after one week of no treatment. Serum IGFBP‐3 was abnormally low (0·70·0±37 mg/l) and decreased significantly further during IGF‐I treatment (to 0·48·0±28 mg/l) (P > 0·065). conclusions The finding that serum IGFBP‐3 is low in Laron type dwarfism, a disease due to molecular defects in the GH receptor, is compatible with the hypothesis that this IGF binding protein is GH‐dependent. On the other hand the decrease during IGF‐I administration and concomitant suppression of GH secretion may denote either that GH activity is not completely blocked in this syndrome or that there are additional mechanisms regulating IGFBP‐3 synthesis