Review Question - QID 108430

The most likely diagnosis in this case is Sheehan syndrome, which is caused by anterior pituitary apoplexy related to peripartum hypotension. Levels of all hormones regulated by the pituitary gland will be abnormal in this disorder while the renin-angiotensin axis governing aldosterone secretion is not affected.

The proximity of this patient’s disorder to the time of delivery suggests that the syndrome is related to pregnancy. Symptoms that should be recognized are cold intolerance, fatigue, and weight gain (suggestive of hypothyroidism) and failure of lactation (suggestive of prolactin deficiency). These symptoms indicate an endocrine defect. This suspicion is further supported by fatigue and hypotensive episodes (consistent with of low levels of thyroid hormone and cortisol). In the setting of peripartum blood loss (such as that seen in placenta accreta), a major endocrine-related complication is Sheehan syndrome. It occurs when the pituitary gland is infarcted during episodes of hypotension leading to global pituitary hormones deficiency. As a result, hormones such as aldosterone that are regulated independently of the pituitary gland will more likely remain normal in patients with Sheehan syndrome.

Incorrect Answers:
Answer 1: Antidiuretic hormone (or vasopressin) is responsible for regulating serum osmolality and is produced in the hypothalamus before being released by nerve terminals located in the posterior pituitary gland. Its level would not be normal. As to whether the levels would be increased or decreased may vary as their have been reports of increased and decreased ADH secretion

Answer 3: Cortisol production by the zona fasciculata of the adrenal cortex is regulated by the level of adrenocorticotropic hormone produced by basophilic cells in the anterior pituitary gland. Pituitary infarction would therefore lead to a decrease in cortisol production.

Answer 4: Luteinizing hormone is produced by the anterior pituitary gland and would decrease in Sheehan syndrome.

Answer 5: Thyroid hormone is regulated by thyroid stimulating hormone produced in the anterior pituitary gland. Thus, thyroid hormone production is decreased in Sheehan syndrome.

Bullet Summary:
Lactation failure in the peripartum period is often due to pituitary infarction (Sheehan syndrome) secondary to blood loss. All hormones regulated by the pituitary gland will be affected and manifest as their related deficiency symptoms. Hormones regulated independently of the pituitary gland remain unaffected.