A 25-year-old female presents with the acute onset of cessation of lactation. She delivered her first child several months ago & has been breast-feeding since then. She reports that she has not menstruated since the delivery. She also says that lately she has been tired & has been feeling cold all of the time. Laboratory workup reveals a deficiency of ACTH & other anterior pituitary hormones. What is the most likely cause of this patient's signs & symptoms?

(D) Sheehan's syndrome # HYPOPITUITARISM results from destructive processes that involve the adenohypophysis (anterior pituitary).> These processes may be acute (sudden) or chronic. Sheehan's syndrome, also known as postpartum pituitary necrosis, results from the sudden infarction of the anterior lobe of the pituitary This can occur with obstetric complications, such as hemorrhage or shock.> Pituitary gland normally doubles in size during pregnancy, hypovolemia during delivery decreases blood flow & may result in infarction of the anterior pituitary. Sheehan's syndrome produces symptoms of hypopituitarism. The initial sign is cessation of lactation, which may be followed by secondary amenorrhea due to the loss of gonadotropins.> Other signs of hypopituitarism include hypothyroidism & decreased functioning of the adrenal gland. Acute destruction of the pituitary is also associated with DIC & thrombosis of the cavernous sinus.> Chronic causes of hypopituitarism include nonsecretory chromophobe pituitary adenomas, empty sella syndrome, & suprasellar (hypothalamic) tumors.> Nonsecretory chromophobe adenomas present as space-occupying lesions that cause decreased hormone production.> Gonadotropins are lost first, which results in signs of hypogonadism.> Types of chromophobe adenomas include null cell adenomas (no cytoplasmic granules), chromophobes (sparse granules), & oncocytic adenomas (increased cytoplasmic mitochondria). The term pituitary apoplexy refers to spontaneous hemorrhage into a pituitary tumor, while the empty sella syndrome is caused by a defective diaphragm seilae, which permits CSF from the third ventricle to enter the sella.> It may also be secondary to infarction or necrosis. A CT scan reveals the sella to be enlarged or to appear empty.