Sheehan syndrome: postpartum necrosis of the pituitary gland. Usually occurs following postpartum hemorrhage, but can also occur even without clinical evidence of hemorrhage.
During pregnancy, hypertrophy of prolactin-producing regions increases the size of the pituitary gland, making it very sensitive to ischemia.
Blood loss during delivery/postpartum hemorrhage → hypovolemia → vasospasm of hypophyseal vessels → ischemia of the pituitary gland → empty sella turcica on imaging
No hyperpigmentation (unlike primary adrenal insufficiency, POMC/MSH is not elevated).
No hyperkalemia or salt-wasting (aldosterone synthesis is regulated by RAAS, not ACTH). c
Cortisol normally exerts negative feedback on ADH secretion. A deficiency in cortisol removes this inhibition, leading to increased ADH secretion (dilutional hyponatremia) and hypovolemic/euvolemic hyponatremia. c
Females: Amenorrhea, infertility, vaginal atrophy, loss of libido.
Males: Erectile dysfunction, testicular atrophy, loss of libido, decreased muscle mass.
GH deficiency:
Adults: Increased abdominal adiposity, decreased bone mineral density, vague fatigue.
Children: Short stature, severe growth deceleration.
PRL deficiency:
Inability to lactate postpartum (highly specific for Sheehan syndrome).
Pituitary Apoplexy presentation:
Sudden-onset, severe “thunderclap” headache, meningismus, fever.
Bitemporal hemianopsia (optic chiasm compression), ophthalmoplegia (CN III, IV, VI palsy).
Cardiovascular collapse due to acute, life-threatening ACTH deficiency.
Diagnostics
Treatment
Treat the underlying cause: For example, surgical resection of a pituitary adenoma.
Hormone Replacement Therapy: This is the cornerstone of treatment and is typically lifelong.
Glucocorticoids (hydrocortisone, prednisone): Replace for ACTH deficiency. This must be done FIRST before thyroid hormone replacement to prevent precipitating a life-threatening adrenal crisis.
Levothyroxine: Replace for TSH deficiency.
Sex Hormones: Testosterone for men; estrogen and progesterone for women.
Growth Hormone (somatropin): Used for children with GH deficiency and may be used in adults to improve body composition and quality of life.
Desmopressin (DDAVP): Used if there’s concomitant posterior pituitary damage leading to diabetes insipidus.