Shrinkage of a primary thyrotropin-secreting pituitary adenoma treated with the long-acting somatostatin analogue octreotide (SMS 201-995).

The long-acting somatostatin agonist octreotide can control TSH hypersecretion from most thyrotropic adenomas. Octreotide therapy has even been shown to improve chiasmal dysfunction. We report another patient in whom octreotide therapy was associated with gradual suppression of TSH hypersecretion, which escaped partially, dramatic and very rapid and sustained improvement of chiasm compression, and dramatic and sustained shrinkage of an unresectable TSH-secreting pituitary tumour. Unusual and prolonged gastrointestinal adverse reactions eventually disappeared except for steatorrhea. In conclusion, octreotide may be considered as first line treatment in patients with unresectable thyrotropic adenomas.