EFFECT OF 4 WEEKS OF OCTREOTIDE TREATMENT ON PROLACTIN, THYROID-STIMULATING HORMONE AND THYROID-HORMONES IN ACROMEGALIC PATIENTS - A DOUBLE-BLIND PLACEBO-CONTROLLED CROSS-OVER STUDY

We aimed to test the hypothesis, that octreotide has a suppressive eff ect on unstimulated and TRH-stimulated PRL levels in both normo- and h yperprolactinaemic acromegalic patients, and besides to evaluate the e ffect of octreotide on unstimulated TSH and thyroid hormones. The pres ent study is a doubleblind placebo-controlled cross-over trial; the 12 acromegalic patients were treated with octreotide or placebo (300 mu g/d) for 4 weeks separated by a 12 weeks washout period. Before and af ter each 4 weeks period a TRH-test (200 mu g iv) was performed and ser um GH and PRL levels were determined. Serum TSH and thyroid hormones w ere determined after 0, 2, 3, and 4 weeks. In the whole group unstimul ated PRL levels were 18 mu g/l +/- 5 before and 7 mu g/l +/- 1 during octreotide treatment (p < 0.01). The PRL lowering effect of octreotide was significantly more pronounced in hyperprolactinemic patients comp ared to normoprolactinaemic patients (p < 0.05), Patients with the hig hest pretreatment PRL levels had the most pronounced percentage suppre ssion of unstimulated PRL levels during octreotide treatment, Eight ou t of 12 patients had a TRH-stimulated PRL response greater than or equ al to 100%, both during placebo and octreotide treatment, but in the g roup as a whole maximal TRH-stimulated PRL levels were suppressed duri ng octreotide treatment, PRL levels were 50 mu g/l +/- 20 before and 1 8 mu g/l +/- 3 during octreotide treatment (p < 0.05). Unstimulated GH levels were 48 mU/l +/- 15 before and 13 mU/l +/- 2 during octreotide treatment (p < 0.01). Serum total T-3 was significantly reduced durin g octreotide treatment (p < 0.05); serum TSH, total T-4 or free T-4 in dex were not significantly changed during treatment. We conclude that patients with acromegaly and hyperprolactinemia will normalize PRL lev els during 4 weeks of octreotide treatment and octreotide will reduce total T-3 levels in acromegalic patients.