This woman has amenorrhea and visual complains consistent with bitemporal hemianopia. This presentation is consistent with a lactotroph adenoma (prolactinoma), which can also contribute low bone mineral density.
Increased levels of prolactin can be the result of both physiologic and pathologic causes. The most common pathologic causes are prolactinoma, decreased inhibition of prolactin secretion by dopamine secondary to hypothalamic or pituitary disease, and decreased clearance of prolactin. Prolactinomas are benign tumors of lactotroph cells in the pituitary. They are diagnosed more frequently in women given their propensity to disrupt the menstrual cycle. Other common symptoms of these tumors include fatigue, vaginal dryness, decreased libido, galactorrhea, headaches, and visual changes.
Lake et al. discuss the treatment of prolactinomas in their review. Most can be treated using dopamine agonists. Dopamine inhibits the release of prolactin from the anterior pituitary, leading to a reduction in symptoms, decreased tumor size, and resumed menstrual cycles for premenopausal women. The most common side effects of this treatment are nausea, vomiting, and fatigue.
Melmed et al. discuss the diagnosis of prolactinoma. They first recommend confirming the diagnosis of hyperprolactinemia with a serum prolactin test. The test can be performed at any time of day. Elevated levels confirm the diagnosis and levels above 500 µg/liter are diagnostic of a macroprolactinoma. At that point, nonphysiologic forms of hyperprolactinemia should be ruled out including medication use, renal failure, and parasellar tumors.
Illustration A is an anatomical drawing of the anterior and posterior pituitary as it sits in the sella tursica. Illustration B is an MRI of a pituitary macroadenoma. An adenoma of this size would likely cause considerable neurologic symptoms including headaches and visual disturbances.
Answer 1: While the patient has not had a menstrual cycle, the negative pregnancy test makes this unlikely.
Answer 2: Breast masses do not typically secrete prolactin and would be an unlikely cause.
Answer 4: An enlarged thyroid can be associated with certain autoimmune conditions such as Graves' disease, which can present with heat intolerance, weight loss, and a tremor.
Answer 5: While decreased renal clearance of prolactin can lead to hyperprolactinemia, there is nothing in this patient's history to suggest she has renal impairment.
Lake MG, Krook LS, Cruz SV. Pituitary adenomas: an overview. Am Fam Physician. 2013 Sep 1;88(5):319-27
PMID:24010395 (Link to Abstract)
Melmed S, Casanueva FF, Hoffman AR, Kleinberg DL, Montori VM, Schlechte JA, Wass JA; Endocrine Society. Diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline
PMID:21296991 (Link to Abstract)