A 28-year-old with history of severe postpartum hemorrhage 1 month ago is sent to the ED from primary care clinic for hypotension and worsening weakness and fatigue over the last few days. On review of systems, she notes that she has been having trouble with her memory, cold intolerance, low appetite, and has been unable to breastfeed since her previous discharge from the hospital. Vitals are:
Basic metabolic panel shows:
Complete blood count demonstrates:
Thyroid-stimulating hormone (TSH) is 0.1 mIU/L (normal 0.5-4 mIU/L). Injection of 500 µg of thyrotropin-releasing hormone elicits no increase in serum TSH or prolactin.
Which of the following hormones is most likely to have normal levels?
A. AldosteroneCorrect Answer: A
This patient has symptoms of new adrenal insufficiency and hypothyroidism that is unresponsive to an injection of thyrotropinreleasing hormone. This is indicative of destruction of pituitary tissue responsible for adrenocorticotropic hormone and TSH production. Her history of severe postpartum hemorrhage, along with agalactorrhea, strongly suggests Sheehan syndrome as the etiology of her symptoms.
Sheehan syndrome is hypopituitarism caused by ischemic damage from excessive hemorrhage. The pituitary is enlarged and more metabolically active during pregnancy and, thus, more prone to hypoxemia and infarction from hypovolemic shock. The blood vessels are also more susceptible to vasospasm due to elevated estrogen levels.
Damage to the pituitary can be variable; some or all hormones produced by the pituitary may be affected, as well as those downstream. These include ACTH, TSH, luteinizing hormone, follicle-stimulating hormone, prolactin, growth hormone, and melanocyte-stimulating hormone. Of note, ACTH stimulates adrenal glands to produce cortisol and other hormones, but aldosterone production is regulated by angiotensin II and serum potassium levels. Thus, aldosterone levels should be unaffected in Sheehan syndrome.
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