Reduction in size of a thyrotropin- and gonadotropin-secreting pituitary adenoma treated with octreotide acetate (somatostatin analog).

TSH as well as alpha-subunit, secretion has been shown to decrease after the administration of the somatostatin analog octreotide acetate (SMS 201-995). We have studied a 59-yr-old, male patient with a TSH- and gonadotropin-secreting tumor who, because of severe cardiomyopathy, was treated with long-term somatostatin analog rather than surgical resection of the pituitary tumor. Thirteen weeks of treatment with thrice daily sc injection of 100 micrograms octreotide acetate resulted in decreased TSH and alpha-subunit secretion, normal serum thyroid hormone levels, reduction in LH and testosterone level, and significant tumor size reduction. Long-term treatment for 51 weeks has not been associated with any significant side effects. We have shown that octreotide acetate may be a therapeutically valuable modality for certain patients with neoplastic inappropriate secretion of TSH (NIST). A probable effect of octreotide acetate on neoplastic gonadotropes, as evidenced by the reduction of the LH level with a concomitant decrease in testosterone level, is, likewise, suggested.