True hyperprolactinemia in men without visible pituitary adenoma

Purpose: Men with mild to moderate hyperprolactinemia rarely present with normal pituitary on MRI with no visible adenoma, a condition entitled also “idiopathic hyperprolactinemia” or “non-tumoral hyperprolactinemia”. We have characterized a cohort of hyperprolactinemic men with normal pituitary imaging. Design: We have identified 13 men with true hyperprolactinemia and normal pituitary MRI. Baseline clinical and hormonal characteristics and response to medical treatment were retrospectively retrieved from medical records. Results: Mean age at diagnosis was 51 ± 16 years (range, 20–77); mean serum prolactin level at presentation was 91 ng/ml (range, 28–264), eight men presented with low baseline testosterone. Initial complaints leading to diagnosis included sexual dysfunction in ten men and gynecomastia in five. All patients were treated with cabergoline, except for one who was given bromocriptine; none required pituitary surgery. All patients normalized prolactin and testosterone with subsequent clinical improvement reported by most men. Currently, after a mean follow-up of 72 months, ten patients continue treatment with caborgoline (median weekly dose, 0.25 mg), whereas three men discontinued treatment. Conclusions: Men with symptomatic hyperprolactinemia may rarely present with normal pituitary imaging. Medical treatment can lead to hormonal improvement with clinical benefit.