Effect of a long-acting somatostatin analogue (SMS 201-995) on a growth hormone and thyroid stimulating hormone-producing pituitary tumor.

A 46-year-old woman with acromegaly and hyperthyroidism due to a pituitary adenoma. She had high serum thyroid-stimulating hormone (TSH) levels and very high serum growth hormone (GH) levels. Transsphenoidal removal of the tumor, post-operative irradiation, frontal craniotomy for removal of residual tumor and large-dose bromocriptine therapy were carried out consecutively. After therapy, serum GH levels gradually decreased, but not to the normal range, and serum TSH levels remained at inappropriately normal levels. Using immunoperoxidase techniques, GH-, TSH- and follicle-stimulating hormone (FSH)-containing cells were demonstrated in the adenoma. A long-acting somatostatin analogue (SMS 201-995, 600 micrograms/day) suppressed the serum GH level to the normal range with a concomitant suppression of TSH. Furthermore, the paradoxical serum GH responses to TRH and LH-RH were slightly improved. No important subjective side-effects were noted. Therefore, SMS 201-995 appeared to be a very effective drug in this patient with a GH- and TSH-producing pituitary tumor.