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Difficulty: MediumReproductive Endocrinology and Infertility

A 31-year-old woman comes to the physician because she has not had a menstrual period since giving birth 13 months ago. Her pregnancy was complicated by placental abruption and severe postpartum hemorrhage requiring the transfusion of 4 units of packed red blood cells. She reports that after delivery, her "milk never came in" despite frequent attempts to breastfeed. Over the past 6 months, she has experienced progressive fatigue, cold intolerance, and occasional dizzy spells when standing up. Physical examination shows a blood pressure of 90/60 mm Hg. There is thinning of the lateral eyebrows and an absence of axillary and pubic hair. Pelvic examination shows vaginal mucosal atrophy. Which of the following is the most likely underlying mechanism for this patient's current symptoms?

  1. A
    Autoimmune destruction of thyroid follicular cells
  2. B
    Abnormal frequency of gonadotropin-releasing hormone pulsations
  3. C
    Destruction and fibrosis of the endometrial basalis layer
  4. Ischemic necrosis of the anterior pituitary glandAnswer
  5. E
    Sustained physiologic hyperprolactinemia

Answer

Ischemic necrosis of the anterior pituitary gland
The correct answer is ischemic necrosis of the anterior pituitary gland (Sheehan syndrome). During pregnancy, the anterior pituitary gland enlarges and becomes highly vascular, making it exquisitely sensitive to hypoperfusion. A massive postpartum hemorrhage (as seen in this patient with placental abruption requiring transfusions) can lead to ischemic necrosis of the gland. This results in panhypopituitarism. The lack of prolactin causes failure to lactate. The lack of gonadotropins (FSH, LH) causes secondary amenorrhea and vaginal atrophy. The lack of TSH causes secondary hypothyroidism (fatigue, cold intolerance, delayed reflexes). Finally, the lack of ACTH leads to secondary adrenal insufficiency, causing hypotension and the loss of axillary and pubic hair (which are dependent on adrenal androgens).

Step-by-Step Solution

1
Analyze the patient's obstetric history.
The patient experienced placental abruption and massive postpartum hemorrhage requiring blood transfusions.
Identifying severe peripartum hypovolemia establishes the primary risk factor for pituitary ischemia.
2
Evaluate the patient's current symptoms and physical exam findings.
Failure to lactate (prolactin deficiency), secondary amenorrhea and vaginal atrophy (FSH/LH deficiency), fatigue and cold intolerance (TSH deficiency), and hypotension with loss of pubic hair (ACTH deficiency).
Connecting these symptoms reveals a pattern of multiple anterior pituitary hormone deficiencies (panhypopituitarism).
3
Correlate the risk factor with the clinical presentation.
Massive postpartum hemorrhage followed by panhypopituitarism indicates Sheehan syndrome.
The pituitary gland enlarges during pregnancy, making it highly susceptible to ischemic necrosis during episodes of profound hypotension.

Key Concept

Sheehan syndrome (postpartum pituitary necrosis) presents with panhypopituitarism following massive postpartum hemorrhage, characterized by failure to lactate, amenorrhea, and signs of secondary hypothyroidism and adrenal insufficiency.
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Topics

Reproductive Endocrinology and Infertility

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