title: The influence of serum cortisol levels on growth hormone responsiveness to GH-releasing hormone plus GH-releasing peptide-6 in patients with hypocortisolism.
abstract: The aim of this study was to evaluate the influence of circulating cortisol levels on the somatotroph responsiveness to the most potent stimuli of growth hormone (GH) secretion, the GHRH+GHRP-6 test. We studied 12 patients with hypocortisolism (10 with Addison's disease and 2 with isolated ACTH deficiency) before and after glucocorticoid (GC) replacement therapy and compared them with 14 healthy subjects. In the 10 patients with Addison's disease, GH responses (GH peak, microg/L) to GHRH+GHRP-6 were similar both during GC, (68.2+/-12.8) and off GC (60.3+/-14.1) therapy and did not differ from those in controls (61.5+/-6.0). In a subgroup of 4 patients with newly diagnosed Addison's disease, GH responsiveness to GHRH+GHRP-6 prior to GC replacement (26.4+/-4.1) was significantly lower than in the 6 patients with long-standing Addison's disease after short-term GC withdrawal (82.9+/-18.2). In the newly diagnosed Addison's patients, after one month of GC replacement, mean GH peak value increased to 40.7+/-11.8. In the 2 patients with isolated ACTH deficiency, GH responses to GHRH+GHRP-6 did not differ off and on GC therapy (60.3+/-14.1 and 41.5+/-2.0, respectively). Our data suggest that short-term GC deprivation does not have a major impact on GH responsiveness to GHRH+GHRP-6. However, in patients with long-standing hypocortisolism, GH response is blunted but still within normal range (> 15 microg/L).
authors.affiliation: Institute of Endocrinology, University Clinical Center, Belgrade, Yugoslavia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Pekic
authors.forename: Mirjana
authors.initials: M
authors.lastname: Doknic
authors.forename: Marina
authors.initials: M
authors.lastname: Djurovic
authors.forename: Svetozar
authors.initials: S
authors.lastname: Damjanovic
authors.forename: Milan
authors.initials: M
authors.lastname: Petakov
authors.forename: Dragana
authors.initials: D
authors.lastname: Miljic
authors.forename: Carlos
authors.initials: C
authors.lastname: Dieguez
authors.forename: Felipe F
authors.initials: FF
authors.lastname: Casanueva
authors.forename: Vera
authors.initials: V
authors.lastname: Popovic