Effect of a Somatostatin Analogue on Trophic Hormone Levels in Acromegalic Patients with Elevated hGH after Adrenomectomy and Treatment with Bromocriptine

Five female acromegalic patients who had undergone surgical adenomectomy, but still had elevated hGH serum levels, were treated with bromocriptine, 5-15 mg daily, for at least 4 months without a satisfactory response. In an attempt to lower serum hGH levels, p-NH₂-Phe⁴-D-Trp⁸-somatostatin was administered, 100 μg as an i.v. bolus, followed by infusion of 250 μg over a 4 hour period. The analogue decreased hGH levels by about 50% in 3 out of 5 patients, both during bromocriptine treatment and also in its absence. Of the remaining two patients, one showed a decrease in hGH levels in response to the analogue only during bromocriptine treatment and the other only without it. Saline infusion after bromocriptine administration did not induce a decrease in hGH levels in three of these patients. Somatostatin analogue caused a fall in serum insulin levels in all but one patient, who had diabetes mellitus and in whom serum insulin was undetectable. Both hGH and insulin levels showed a significant rebound after infusion of the analogue, but returned to basal levels within 24 hours. Prolactin did not change during the analogue infusion in 4 patients with normal PRL levels. However, in one patient in whom prolactin and hGH levels were elevated during bromocriptine treatment, the infusion of somatostatin analogue decreased both hormones. The analogue induced no changes in serum TSH, FSH and LH levels of any of the patients.