What is the likely cause of hyperprolactinemia in a patient with high serum prolactin levels?

The presence of hyperprolactinemia, indicated by high serum prolactin levels, is most commonly due to a prolactin-secreting pituitary tumor, known as a prolactinoma. This benign neoplasm arises from lactotroph cells in the pituitary gland, leading to excessive production and secretion of prolactin. Elevated prolactin levels can result in various clinical symptoms, such as galactorrhea (milk secretion), menstrual disturbances, and infertility.

Understanding the condition helps clarify its implications. Prolactinomas are generally the most frequent cause of clinically significant hyperprolactinemia and can be confirmed through imaging studies such as MRI, which can reveal the presence of a tumor in the pituitary gland.

While hypothyroidism can lead to increased prolactin levels due to elevated thyrotropin-releasing hormone (TRH), and stress can transiently elevate prolactin levels, these conditions are not as definitive in causing persistent hyperprolactinemia compared to a prolactin-secreting tumor. Polycystic ovary syndrome (PCOS) is also associated with hormonal imbalances but is not primarily recognized for significant elevation in prolactin levels. Thus, the progress