Basal and TRH-stimulated prolactin in patients with pituitary tumours.

The diagnostic value of the assessment of prolactin (PRL) secretion in reaction to thyrotrophin releasing hormone (TRH) was investigated in twenty-four patients who had all radiological signs of a pituitary tumour and symptoms of hypogonadism and/or galactorrhoes. It was found that in these patients a PRL response to TRH can be present or absent, independent of the size of the tumour and/or the presence of suprasellar extension of the tumour. The measurement of several basal plasma PRL concentrations in combination with lateral tomography of the sella turcica seem to be a good screening for the existence of a prolactin producing pituitary adenoma and no important additional information is obtained by a TRH-test.