Macroprolactinemia in a young man and review of the literature.

A 21-year old man, complaining of headaches and fatigue, with a negative past medical history and a normal clinical examination, underwent a hormonal investigation which revealed hyper-prolactinemia and intact pituitary-gonadal axis. Drug-induced hyperprolactinemia was excluded. Pituitary magnetic resonance imaging indicated a microadenoma in the right part of the gland, with a diameter of 1.5mm. No medical treatment was given as the patient had no symptoms relevant to prolactin excess. The PEG precipitation test was carried out and showed 7% recovery, which was diagnostic of the macroprolactinemia. Relatively few cases of macroprolactinemia have been published in the literature, although the condition is regarded as a fairly common cause of hyperprolactinemia. Macroprolactinemic men represent 10% of published cases.