PRL stands for prolactin, a peptide hormone secreted by the pituitary gland. The role of prolactin is to promote the development of the mammary glands and to facilitate and maintain the lactation process, and it is significantly increased in pregnant and lactating women. Under normal circumstances, a mild increase in prolactin may also occur under the influence of emergencies, sexual intercourse, certain medications, etc., and is of little clinical significance. If prolactin levels are significantly elevated, this can be seen in pituitary tumors, which can present with hyperprolactinemia if they are predominantly prolactin-secreting, or idiopathic hyperprolactinemia can occur. If prolactin levels are significantly elevated, a pituitary MRI is required to rule out pituitary prolactinoma and, if necessary, to treat with prolactin-lowering medications.