What type of pituitary adenoma is most commonly found in patients?

Prolactinomas, or prolactin-secreting adenomas, are indeed the most common type of functioning pituitary adenoma. These tumors secrete excess prolactin, leading to a variety of symptoms such as galactorrhea, menstrual disturbances, and infertility in women, and decreased libido and impotence in men. The high prevalence of prolactinomas is primarily due to the high levels of circulating prolactin that can occur with these tumors, which can cause significant clinical symptoms and are relatively more easily diagnosed compared to other types of adenomas.

In contrast, while ACTH-secreting adenomas can lead to Cushing's disease and GH-secreting adenomas can cause acromegaly, these conditions are less commonly encountered in clinical practice when compared to prolactinomas. TSH-secreting adenomas are rare. Therefore, the prevalence and clinical impact of prolactinomas make them the most commonly encountered type of pituitary adenoma in patients.