USMLE® Step 1 style questions USMLE
A 32-year-old man comes to his outpatient provider because of headaches that began five-months ago. The patient reports that the headaches are worse in the morning and improve over the day. In addition, the patient endorses reduced body hair. He does not use any medications. Temperature is 37.4°C (99.3°F), pulse is 68/min, respirations are 20/min, and blood pressure is 125/72 mmHg. Physical exam is notable for restricted peripheral vision and white watery discharge from the nipples. Further review of the patient’s history will most likely reveal which of the following findings?
Content Reviewers:Rishi Desai, MD, MPH
With hyperprolactinemia, hyper- means above, -prolactin refers to the hormone produced by the pituitary gland, and -emia refers to the blood, so hyperprolactinemia means higher than normal prolactin levels in the blood.
Normally, at the base of the brain, there’s a small pea-sized gland called the pituitary gland.
Apart from milk production, high levels of prolactin also inhibit the release of gonadotropin releasing hormone from the hypothalamus, which results in decreased luteinizing and follicle stimulating hormone levels, which in turn, decreases estrogen levels.
In women, this can stop ovulation and menstruation, which is why women typically don’t have a menstrual period while breastfeeding. In women that are not pregnant or breastfeeding, and in men, prolactin levels are usually kept in check by the hypothalamus in two ways.
Dopamine binds to specific receptors on the lactotrophs and inhibits the release of prolactin. The second way is when the hypothalamus secretes thyrotropin releasing hormone, also called prolactin releasing hormone, which can stimulate prolactin release.
If the level of prolactin rises for any reason, then it signals the hypothalamus to release more dopamine, eventually decreasing its own production, a process called negative feedback or feedback inhibition.
Hyperprolactinemia can develop a few different ways. The first is physiologic hyperprolactinemia, which is what happens during pregnancy and lactation - and levels of prolactin typically return back to normal afterwards.
Another cause is a prolactinoma, a type of pituitary adenoma, a benign tumor of lactotroph cells which grow uncontrollably and make excess amounts of prolactin. There are also systemic causes of hyperprolactinemia like hypothyroidism.
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