ABSTRACT
Hyperprolactinemia is most frequently caused by a prolactinoma, which is the most common type of benign pituitary adenoma.1 Prolactinomas < 10 mm are microprolactinomas, and those ≥ 10 mm are macroprolactinomas. Prolactinomas are categorized based on size because their size predicts their behavior. Microadenomas rarely progress in size, while macroadenomas may grow to a considerable size and invade tissue planes. This fits with the finding that macroprolactinomas have a vascular density that is significantly higher than that of microprolactinomas, which suggests they are products of different pathological processes.2 Prolactinomas account for up to 45% of pituitary tumors, occurring with an incidence of 6-10 cases per million annually and a prevalence of 60-100 cases per million.3 Prolactinomas occur more frequently in women during the second through fifth and decade, but the gender disparity disappears in the
fifth decade. The peak incidence occurs during the third decade of life, where the female to male ratio is 14.5:1.1
The gender disparity in the incidence of prolactinomas may be somewhat fallacious. Men may not seek
immediate medical attention for signs of hyperprolactinemia, such as impotence and decreased libido. This may explain why men have a higher frequency of more advanced lesions, such as macroadenomas and tumors with mass effects. Women, on the other hand, most commonly experience problems such as infertility, amenorrhea, or galactorrhea: signs that are more likely to prompt a visit to the clinician. It is possible that these differences account for some of the gender disparity in the incidence of the disease.
