One cause of hyperprolactinaemia is the presence of the biologically inactive macroprolactin in the serum. This can show up as high prolactin in some types of tests, but is asymptomatic. Another cause of hyperprolactinaemia is a prolactinoma, a pituitary gland tumor.
Symptoms and signs
Hyperprolactinaemia is a common cause of menstrual problems in women, and high levels of prolactin can cause gynecomastia (breast enlargement) in men. It can also cause galactorrhea.
The hormone prolactin is downregulated by dopamine and is upregulated by estrogen.