THE GROWTH-HORMONE, PROLACTIN AND TSH RESPONSE TO TRH AND L-DOPA IN PATIENTS WITH HYPERPROLACTINEMIA AND A NORMAL-SIZED SELLA TURCICA MAY DENOTE A PITUITARY-ADENOMA

Abstract. Forty‐one patients with hyperprolactinaemia and suspected prolactinomas were studied. Growth hormone (GH) and thyrotropin (TSH) secretory patterns after thyrotropin releasing hormone (TRH) were affected in the majority of patients. The disturbances were observed regardless of tumour size as indicated by the radiological sella size. In patients with hyperprolactinaemia and normal‐sized sella turcica, an abnormal GH and TSH response to TRH can be helpful in the diagnosis of a microadenoma. The hyperprolactinaemia per se and its effect on dopaminergic hypothalamic neurones may be the cause of the GH and TSH response. By contrast, many patients with macroprolactinomas showed insufficient GH secretory capacity. 1990 Blackwell Publishing Ltd