Thyrotoxicosis in a patient with secondary hypothyroidism.

We have described a patient with panhypopituitarism who developed thyrotoxicosis. There is a widespread belief that pituitary thyrotropin (TSH) is not a pathogenetic factor in most patients with thyrotoxicosis. Due to technical reasons, however, it has been difficult to entirely exclude the role(s) of TSH in the development of thyrotoxicosis. In this report hyperthyroidism appeared in a patient with TSH deficiency proved by the lack of response to TRH administration. This is the first known case in which TRH stimulation demonstrated total abscence of TSH before the onset of thyrotoxicosis. We cannot exclude the possibility that factors of adenohypophyseal origin play some role in the pathogenesis of thyrotoxicosis, but TSH per se does not play a role in the development of Graves' thyrotoxicosis.