Rare forms of thyrotoxicosis: thyrotropin-secreting pituitary adenomas

Abstract

Thyrotoxicosis most often occurs due to autoimmune diseases of the thyroid gland or a multi-nodular toxic goiter, but it can also be caused by TSH-secreting pituitary adenomas. In the presence of these adenomas, the levels of circulating free T3 and T4 increase in the absence of suppression, even with elevated TSH levels. Incorrect interpretation of results from studies that only measure TSH can lead to erroneous diagnoses and management strategies for patients, including unnecessary surgery or radioactive iodine therapy. This can contribute to the growth of pituitary tumors. Various tests have been used to try to diagnose them, but none have proven to be eff ective. Only laboratory tests in combination with MRI of the pituitary can accurately diagnose and prescribe treatment. When choosing a treatment for TSH-producing pituitary adenomas, preference is given to the surgical method of transsphenoidal adenomectomy. If surgery is not possible or eff ective, the method used to normalize TSH levels is to prescribe somatostatin analogs. In some cases, it is possible to use somatostatin analog therapy before neurosurgery. In exceptional circumstances, radiation therapy may be used, as with other types of adenomas.