••• Chapter 52^ Hypothalamic-Pituitary-Ovarian-Uterine Axis^523
❍ What are the two most common types of pituitary adenomas?
Prolactin-secreting and null cell adenomas.
❍ What is the most common functional pituitary tumor?
Prolactinoma.
❍ Do prolactinomas occur more frequently in men or women?
Women.
❍ What is the most common presenting symptom of a prolactinoma in a woman?
Secondary amenorrhea.
❍ In patients with a prolactinoma and secondary amenorrhea, what percentage have an associated galactorrhea?
50%.
❍ How is the diagnosis of a prolactin-secreting tumor confirmed?
Radiographic evidence of a pituitary lesion with an elevation of serum prolactin.
❍ What pharmaceutical agent has been shown effective in reducing serum prolactin, reducing tumor, and
inhibiting tumor growth?
Bromocriptine (a dopaminergic agonist).
❍ What is hypersecretion of ACTH by the pituitary referred to as?
Cushing disease.
❍ Is Cushing disease more common in men or women?
It is eight times more common in women.
❍ How is the diagnosis of Cushing disease confirmed?
Increased basal plasma cortisol levels with loss of diurnal variation.
Failure of serum cortisol suppression with the low-dose dexamethasone suppression test.
Increased 24-hour urinary-free cortisol excretion (> 100 mg/24 h).
❍ What is the most likely diagnosis in a patient with Cushing syndrome with low plasma ACTH levels?
An adrenal tumor.
❍ What is the most likely diagnosis in a patient with Cushing syndrome with elevated plasma ACTH levels
(>200 pg/mL)?
An ectopic ACTH-secreting tumor.
❍ What is the most common tumor causing ectopic ACTH secretion?
Small cell carcinoma of the lung.