A 45 year old lady presents with galactorrhea, decreased libido, amenorrhea, and high prolactin levels. What is the likely cause of her hyperprolactinemia?

The presentation of galactorrhea, decreased libido, amenorrhea, and elevated prolactin levels suggests a condition where there is an issue with prolactin regulation. Among the given options, a prolactin-secreting pituitary tumor is indeed a key consideration, primarily because such tumors directly cause increased secretion of prolactin, leading to the symptoms observed.

In this scenario, the pituitary tumor, known as a prolactinoma, would directly explain the high levels of prolactin and associated symptoms such as galactorrhea (milk production in non-breastfeeding individuals) and amenorrhea (absence of menstruation), as increased prolactin inhibits the secretion of gonadotropin-releasing hormone (GnRH), which is vital for the normal menstrual cycle and sexual function.

Hypothyroidism might also lead to elevated prolactin levels due to increased thyrotropin-releasing hormone (TRH), which stimulates prolactin secretion. However, it typically causes additional symptoms, such as weight gain, cold intolerance, and fatigue, which are not mentioned in this case. Stress can lead to elevated prolactin levels but usually does not present with chronic and significant hyperprolactinemia or with the