Growth hormone insensitivity syndromes: a preliminary report on changes in insulin‐like growth factors and their binding proteins during treatment with recombinant insulin‐like growth factor I

Publisher Website
Google Scholar
Abstract
Serum levels of insulin‐like growth factor (IGF) binding proteins (IGFBPs) 1, 2 and 3 were studied by radioimmunoassay in 29 patients with growth hormone (GH) insensitivity syndromes (GHIS) before and during treatment with IGF‐I. As in normal subjects, there was a highly significant correlation between IGFs and IGFBP‐3 but not between IGFs and the other binding proteins, though IGFBP‐3 represented only about one‐third of the total IGFBP concentration. In 6 patients with GH deficiency and in 5 patients with GHIS, the pharmacokinetic profile of IGF‐I after a single injection was strongly dependent on the IGFBP‐3 concentration. A slight but significant increase in IGFBP‐3 was observed coincident with the IGF‐I peak, whereas IGFBP‐2 increased after a delay of about 10 hours. In the patients with GHIS, chronic IGF‐I treatment, with twice‐daily injections for 6 months, caused a significant steady decline of IGF‐II and an increase in IGFBP‐2, but had no effect on IGFBP‐1 and IGFBP‐3 levels. During IGF‐I treatment, an inverse relationship between baseline IGF‐I and GH levels was observed. The data suggest that total IGF‐I and IGF‐IL serum levels are determined mainly by IGFBP‐3, even in extreme situations such as GHIS, while other IGFBPs are less important. The IGFBP‐3 concentration seems to be a major regulator of the pharmacokinetics of exogenous IGF‐I, which, in turn, influences IGFBP‐3 levels. This effect of IGF‐I on IGFBP‐3 is not through induction of IGFBP‐3 synthesis, but possibly by reduction of IGFBP‐3 clearance. Finally, IGF‐I administration suppresses GH secretion.

This publication has 28 references indexed in Scilit: