Octreotide, but not bromocriptine, increases circulating insulin-like growth factor binding protein 1 levels in acromegaly

Abstract

de Herder WW, Uitterlinden P, van der Lely A-J, Hofland LJ. Lamberts SWJ. Octreotide, but not bromocriptine, increases circulating insulin-like growth factor binding protein 1 levels in acromegaly. Eur J Endocrinol 1995;133:195–9. ISSN 0804–4643 Twenty-three patients with active acromegaly underwent serum sampling for growth hormone (GH), insulin and insulin-like growth factor binding protein 1 (IGFBP-1) after placebo or single doses of octreotide or bromocriptine. Integrated 24-h serum GH levels decreased by 90% after octreotide and 49% after bromocriptine. A statistically significant correlation between the course of GH levels after octreotide and bromocriptine was observed (p < 0.001). Octreotide, but not bromocriptine, induced a significant increase in integrated 24-h serum IGFBP-1 levels to 37.4 times the baseline values. Bromocriptine caused a non-significant increase in integrated 24-h serum IGFBP-1 levels, which argues against a direct regulatory effect of GH on IGFBP-1 production in acromegaly. In conclusion, octreotide induces in acromegaly the production of IGFBP-1, which occurs independently of the number of somatostatin receptors on the GH-secreting pituitary adenoma. The supposed inhibitory effect of IGFBP-1 on the biological effect of IGF-I might result in an additional clinical benefit in acromegalic patients as compared to treatment directed at the pituitary level. WW de Herder, Department of Internal Medicine III and Clinical Endocrinology, University Hospital Rotterdam, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands