A prolactin level of 50 ng/mL is generally less likely to be considered a pituitary tumor. The cause of hyperprolactinemia can be largely determined by the level of prolactin. In general, if the cause of hyperprolactinemia is a pituitary prolactinoma, the serum prolactin concentration is relatively high, usually greater than about 120ng/mL. Of course, in the clinical encounter of prolactin level greater than 200ng/mL, basically can be diagnosed as prolactinoma, some scholars set this threshold at 300ng/mL. but usually when the prolactin level is less than 100ng/mL, the etiology of pituitary prolactinoma is less likely, but can not be completely excluded. For further diagnosis, an MRI of the craniosynostosis region can be performed to further clarify the presence of a pituitary tumor.