PRL and hyperprolactinemia: While elevated prolactin levels (hyperprolactinemia) can also be caused by other pituitary adenomas through increased intrasellar pressure, known as the stalk effect, or by hypothalamic dysfunction, medications, or various conditions such as pregnancy, liver cirrhosis, and hypothyroidism, these levels are usually well below the prolactin serum levels caused by prolactinomas [2].