A 40-year-old woman is hospitalized due to a femoral neck fracture that occurred when she slipped while stepping out of the bathtub. The patient was diagnosed with a prolactinoma 3 years ago during evaluation of amenorrhea, but she refused medical or surgical treatments. The tumor is being monitored closely and has not increased in size or caused any visual symptoms. The patient has no other medical problems, takes no medications, and does not use tobacco, alcohol, or illicit drugs. She has 3 healthy children and no significant family history. The underlying mechanism for this patient's susceptibility to fracture is most likely to cause which of the following additional manifestations?
Complications of prolactinoma | |
Hyperprolactinemia |
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Mass-effect symptoms |
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Prolactinomas are the most common pituitary tumors. High levels of circulating prolactin, a hormone involved in milk production, result in galactorrhea (nonlactational milk production) and infertility in premenopausal women. Excess prolactin suppresses GnRH secretion from the hypothalamus, leading to reduced secretion of LH (and to a lesser extent FSH) and subsequent hypogonadism, anovulation, and amenorrhea. The resultant estrogen deficiency can manifest as vasomotor symptoms (eg, hot flashes), vaginal dryness and atrophy, and dyspareunia. Because estrogen maintains bone mass in premenopausal women, prolonged estrogen deficiency can lead to osteoporosis and an increased risk for fragility fractures (ie, fractures due to minimal trauma, such as a fall from standing height).
Men with prolactinomas may develop symptoms due to hypogonadism (eg, infertility, decreased libido), but galactorrhea is rare in both men and postmenopausal women as milk production requires estrogen/progesterone priming of the breast tissue. Men with prolactinomas are more likely to present at an advanced stage with mass-effect symptoms (eg, headache, visual field defects) due to compression of surrounding structures.
(Choices A and D) Central hyperthyroidism due to a TSH-secreting (thyrotroph) pituitary adenoma can present with weight loss, palpitations, systolic hypertension, and hyperadrenergic symptoms (eg, hand tremor). Chronic TSH stimulation can also lead to enlargement of the thyroid gland and compressive symptoms (eg, dysphagia). However, compression of thyrotroph cells by an enlarging prolactinoma causes central hypothyroidism.
(Choices B and C) Multiple endocrine neoplasia type 1 (MEN1) is characterized by primary hyperparathyroidism (with hypercalcemia), pituitary tumors (including prolactinoma), and endocrine pancreatic tumors. Complications of hyperparathyroidism include osteoporosis and kidney stones. Stomach ulcers can occur in MEN1 due to hypercalcemia or a gastrin-producing pancreatic tumor (Zollinger-Ellison syndrome). However, most prolactinomas are sporadic and not associated with MEN1. In addition, MEN1 is rare, and this patient's lack of a significant family history makes it even less likely.
Educational objective:
In patients with prolactinoma, high levels of circulating prolactin suppress GnRH secretion from the hypothalamus, leading to reduced secretion of LH and subsequent hypogonadism, anovulation, and amenorrhea. The resulting estrogen deficiency can cause osteoporosis with an increased risk for fragility fractures, and lead to vaginal dryness and atrophy.