Pituitary Adenoma Classification

Large non-functional macroadenomas can compress the pituitary stalk, blocking dopamine's inhibitory signal to normal lactotrophs. This "stalk effect" can raise Prolactin up to 100–200 ng/mL. True prolactinomas usually have prolactin levels much higher and proportional to tumor size (e.g., > 250–500+ ng/mL).