Three Cases With Inappropriate TSH Syndrome

ABSTRACT

Inappropriate thyroid-stimulating hormone (TSH) syndrome or central hyperthyroidism is a rare disorder characterized by inappropriately normal or elevated levels of TSH and elevated levels of T3 and T4. The syndrome is associated with TSH-secreting pituitary adenoma (TSHoma) or thyroid hormone resistance (THR). Thyroid-releasing hormone stimulation test and T3 suppression test can be useful for the differential diagnosis of central hyperthyroidism. In the present study, we report three cases of inappropriate TSH syndrome diagnosed after TRH stimulation and T3 suppression tests.