SERUM PROFILES OF INSULIN-LIKE GROWTH-FACTORS AND THEIR BINDING-PROTEINS IN ADULTS WITH GROWTH-HORMONE RECEPTOR DEFICIENCY TREATED WITH INSULIN-LIKE GROWTH FACTOR-I

Six adult patients with growth hormone receptor deficiency (GHRD) (2 m en, 4 women) with an identical defect in the growth hormone receptor ( GHR) gene, were treated with recombinant human insulin-like growth fac tor I (IGF-I), 40 mug/kg s.c. twice daily, for 7 days. Serum concentra tions of IGF peptide and IGF binding protein-3 (IGFBP-3) were measured by specific radioimmunoassays; serum IGFBPs were also measured by Wes tern ligand blotting. The size distribution of both IGF-I and IGF-II w as measured in serum following size-exclusion fast-performance liquid chromatography. IGF-I treatment resulted in a normalization of serum I GF-I levels on days 1-7 of treatment and a decrease in serum IGF-II le vels. The fall in IGF-II levels and the simultaneous rise in IGF-I lev els, however, resulted in an unchanged total serum IGF level. The low IGFBP-3 values did not significantly change during treatment, whereas there was a slight increase in IGFBP-2 levels. Preliminary analysis of size-fractionated sera suggested an increase in IGF-I levels in the 4 0 and 150 kDa regions at the expense of IGF-II levels. The results sug gest that despite the failure of IGF-I treatment to increase IGFBPs si gnificantly, serum IGFBP concentrations were sufficient to maintain no rmal levels of IGF-I.