A level of prolactin above 200ug/L is very likely to be considered for the diagnosis of pituitary tumor. Elevated prolactin levels are only for pituitary prolactinomas. If it is a combination of other types of pituitary tumors, the endocrine hormone levels associated with it can also be problematic. If the prolactin level is higher than 300ug/L, even if the imaging does not clearly show a pituitary tumor, it is important to consider that there may be a proliferation of pituitary prolactin cells or a pituitary prolactinoma that is not detected by imaging.