A 31-year-old woman comes to the office due to worsening fatigue and abdominal pain for the last month since the birth of her child. She had an emergency cesarean delivery complicated by significant hemorrhage that required transfusion of multiple units of blood. The patient reports that she has been unable to breastfeed and has switched to formula to feed her infant. She also reports occasional dizziness when standing. Temperature is 36.1 C (97 F) , blood pressure is 96/64 mm Hg, and pulse is 96/min. The skin is dry, and the abdomen is nontender to palpation. The patient has sparse axillary and pubic hair. The remainder of the examination is unremarkable. Which of the following laboratory findings would likely be seen in this patient?

Question

Quizplus · Accepted Answer

Explanation: This patient likely has Sheehan syndrome, which is caused by pituitary infarction in the setting of postpartum hemorrhage. As in this patient, patients can have manifestations related to loss of multiple pituitary hormones, including lactation failure (due to loss of prolactin secretion), dry skin and fatigue (due to decreased TSH), and decreased body hair (due to loss of FSH and LH with central hypogonadism), in addition to central/secondary adrenal insufficiency (AI). Sheehan syndrome AI is characterized by cortisol deficiency. It presents with gastrointestinal symptoms (eg, abdominal pain, nausea, anorexia) and loss of vascular tone (eg, orthostatic hypotension). Physiologic stress (eg, surgery, illness) can trigger adrenal crisis and lead to vascular collapse. In addition, because cortisol acts as an inhibitor of antidiuretic hormone, AI often leads to the syndrome of inappropriate antidiuretic hormone release (SIADH) with hyponatremia. Although these features occur in both primary and central (ie, pituitary/secondary, hypothalamic/tertiary) AI, further manifestations differ based on the site of the hormone deficiency: Primary AI (eg, Addison disease) results from destruction of the adrenal cortex. ACTH is increased, and patients develop hyperpigmentation due to cosecretion of melanocyte-stimulating hormone with ACTH. Aldosterone deficiency leads to hyperkalemia, salt wasting, volume contraction, and hypotension (Choice B). Central AI (eg, Sheehan syndrome) results from disease of the pituitary or hypothalamus, leading to a deficiency in ACTH; skin hyperpigmentation does not occur. Because the adrenal cortex remains intact, aldosterone synthesis (primarily regulated by the renin-angiotensin-aldosterone system) is unaffected and the potassium is normal. Hypotension can occur but is typically mild. (Choice C) This patient has Sheehan syndrome, which causes secondary AI and results in low ACTH. Primary AI causes elevated ACTH and hyponatremia, but the potassium is typically elevated. (Choice D) Hyperaldosteronism (Conn syndrome) results in elevated serum sodium and low potassium. ACTH is normal. (Choice E) Although secondary adrenal insufficiency results in low ACTH, the serum potassium would be normal due to the continued effects of aldosterone. Educational objective: Adrenal insufficiency results in gastrointestinal symptoms and loss of vascular tone (eg, orthostatic hypotension); hyponatremia is common due to the syndrome of inappropriate antidiuretic hormone. Unlike patients with primary adrenal insufficiency (eg, Addison disease), patients with central (secondary or tertiary) adrenal insufficiency do not develop hyperkalemia or skin hyperpigmentation.

A 31-Year-Old Woman Comes to the Office Due to Worsening