TRH and hyperplasia: Primary hypothyroidism is characterized by loss of thyroxine feedback inhibition and overproduction of thyrotropin releasing hormone (TRH), which might result in reactive pituitary hyperplasia.[1–5] However, pituitary adenoma secondary to primary hypothyroidism is extremely rare and usually underdiagnosed.[6,7] The pathogenic mechanism of this entity remains unclear, and the clinical characteristics, as well as the therapeutic regimen, have not yet to be well elucidated.