Interrelationship between TSH- and prolactin secretion in patients with prolactinoma and autoimmune thyroiditis

The relationship between the TSH and prolactin (Prl) responses to TRH has been investigated in 36 patients with prolactinoma, in 12 patients with symptomless autoimmune thyroiditis (SAT) and in 10 patients with Graves's disease in remission (GD). Autoimmune thyroiditis in combination with prolactinoma was found in 3 patients. The TSH -response was exaggerated in 4 prolactinoma patients without autoimmune thyroiditis. Moreover, in the patients with prolactinoma and intact function of the non-tumours pituitary gland the mean TSH increment was higher than in the controls. In patients with SAT, on the other hand, the Prl-response to TRH was significantly greater than that in the controls and in patients with GD. The significance of these findings is not obvious but they suggest that TRH may be involved in the development of prolactin secreting adenomata.