Production of the alpha-subunit of glycoprotein hormones by pituitary adenomas.

Positive immunoreactions with alpha-subunit antibodies were present in 43% of biopsy samples obtained from 147 subsequently operated pituitary adenomas representing all major endocrine types (57 endocrine inactive adenomas, 43 prolactinomas, 30 adenomas causing acromegaly, and 17 adenomas causing Cushing's disease or Nelson's syndrome). Marked variations of the incidence, however, were found among the individual endocrine groups. Positive reactions were present in 63% of endocrine inactive adenomas, 57% of adenomas causing acromegaly, 35% of ACTH-secreting adenomas, and 9% of prolactinomas. A positive alpha-subunit reaction was accompanied in a minority of cases only with positive glycoprotein hormone-beta-subunit reactions. There were 21 pure alpha-subunit adenomas in the group of endocrine inactive adenomas.