Hyperprolactinemia in men: clinical and biochemical features and response to treatment.

Hyperprolactinemia induces hypogonadism by inhibiting gonadotropin-releasing hormone pulsatile secretion and, consequently, follicle-stimulating hormone, luteinizing hormone, and testosterone pulsatility. This leads to spermatogenic arrest, impaired motility, and sperm quality and results in morphologic alterations of the testes similar to those observed in prepubertal testes. Men with hyperprolactinemia present more frequently with a macroadenoma than a microadenoma. Symptoms directly related to hypogonadism are prevalent. In men hypogonadism leads to impaired libido, erectile dysfunction, diminished ejaculate volume, and oligospermia. It is present in 16% of patients with erectile dysfunction and in approx 11% of men with oligospermia. Treatment with bromocriptine or cabergoline (CAB) is effective in men with prolactinomas, with a response that is in general comparable to treatment in women. Seminal fluid abnormalities rapidly improve with CAB treatment, while other dopaminergic compounds require longer periods of treatment. Moreover, to improve gonadal function in men, the integrity of the hypothalamic-pituitary-gonadal axis is necessary. New promising data indicate that a substantial proportion of patients with either micro- or macroprolactinoma do not present hyperprolactinemia after long-term withdrawal from CAB. Whether this corresponds to a definitive cure is still unknown, but treatment withdrawal should be attempted in patients achieving normalization of prolactin levels and disappearance of tumor mass to investigate this issue.