GH1 and pituitary gland adenoma: Studies about prolactin co-expression of GH-producing pituitary adenomas as a remission predictor have had heterogeneous results; some studies showed prolactin co-expression is a negative remission predictor [27, 36, 37], some showed it has not predictive role [38–40], and some mentioned prolactin co-expression is positive remission predictor [41].