IGF-I levels rise and GH responses to GHRH decrease during long-term prednisone treatment in man

Glucocorticoid excess is associated with a blunted GH response to GHRH. IGF -I levers in hypercortisolism are controversial and have been reported as l ow normal or high. The aim of this study was to evaluate longitudinally tim e-dependent changes in the GH response to GHRH, IGF-I, IGFBP-3 and albumin values in patients during corticotherapy, Six patients received GHRH before and after one week and one month of prednisone administration (20-60 mg/d, orally). IGF-I, IGFBP-3 and albumin were determined in each test, at time 0. Ten normal controls were also evaluated in one occasion. There were no d ifferences in basal GH values, GH response to GHRH, IGF-I and IGFBP-3 level s between controls and patients before starting corticotherapy. Albumin (g/ l; mean+/-SE) values were lower in patients before treatment (31+/-4) than in controls (43+/-1). After one week of prednisone administration there was a significant decrease in peak GH (mu g/l) levels (before: 18.8+/-7.4; 1 w eek: 5.0+/-1.3), which was maintained after one month (8.1+/-3.5). IGF-I (m u g/l) revels increased significantly, from 145+/-23 to 205+/-52 after one week of therapy, reaching revels of 262+/-32 after one month. IGFBP-3 (mg/l ) values did not increase significantly (before: 2.1+/-0.2; 1 week: 2.5+/-0 .3; 1 month: 2.8+/-0.2). Albumin levels showed a significant rise both afte r one week (36+/-4) and one month (42+/-3) of corticotherapy. In summary, w e observed a marked decrease in the GH response to GHRH after one week and one month of prednisone administration associated with an increase in circu lating IGF-I and albumin values. The physiological implications of these fi ndings are still uncertain. It is possible that glucocorticoids increase he patic IGF-I and albumin synthesis, although other mechanisms may have a rol e. (J. Endocrinol. Invest. 22: 12-17, 1999) (C)1999. Editrice Kurtis.