Prolactinomas: Diagnosis and medical treatment

Prolactinomas are the most common functional pituitary adenomas, accounting for 40% of all pituitary tumors. Microprolactinomas (<10mm) are more frequent in women and macroprolactinomas (≥10mm) usually seen in men. Patients present with hyperprolactinemia-related symptoms including galactorrhea and amenorrhea or ovarian dysfunction in women and erectile dysfunction and decreased libido in men. In addition, symptoms related to the involvement of the optic chiasm and cavernous sinuses leading to visual disturbances or ophthalmoplegia are common in men with invasive macroadenomas. Prolactin levels >200ng/mL indicate a prolactinoma. Levels <100ng/mL may also point to other pathologies including polycystic ovaries, primary hypothyroidism, renal failure, nonprolactinoma pituitary tumors (“stalk effect”), pituitary stalk disease, and medications with dopamine antagonist activity. Dopamine agonists (bromocriptine and cabergoline) are the mainstay of prolactinoma treatment with 80%-90% hormonal remission rate. Patients experience also adenoma shrinkage and clinical and visual improvement. Long-term hormonal remission following dopamine agonist withdrawal is not frequently achieved. Dopamine resistance may require surgery or radiotherapy.