[2][3] This gland is located on the under-surface of the brain, the shape of a cherry and the size of a chickpea and sits in a pit or depression of the sphenoid bone known as the sella turcica (the Turk's saddle).
[4] The pituitary gland works in conjunction with the hypothalamus, and other endocrine organs to modulate numerous bodily functions including growth, metabolism, menstruation, lactation, and even the "fight-or-flight" response.
[6] In some cases, a woman with Sheehan syndrome may be relatively asymptomatic initially; therefore, the diagnosis would not be made until years later when features of hypopituitarism become evident.
[7] In rare instances this syndrome can present acutely with unstable vital signs, dangerously low blood glucose levels, heart failure, or even psychosis.
[9] In addition to menstrual irregularities other signs of sex hormone deficiency are hot flashes, decreased libido, and breast involution.
[12] Adrenal crisis signs and symptoms include hypoglycemia, hypotension, weakness, fatigue, and seizures from severe hyponatremia.
Sheehan's syndrome typically occurs because of excessive blood loss after delivery (post-partum hemorrhage), although there are several risk factors that may contribute to its development.
[5] Thus, if the body enters a state of shock from excessive blood loss in post-partum delivery, the pituitary gland is more susceptible to injury.
[9] One cause of pituitary growth associated with the risk of Sheehan's syndrome is the hyperplasia of lactotrophs which produce prolactin, the hormone responsible for milk production.
Posterior pituitary involvement leading to central diabetes insipidus is much rarer, and typically reflects more extensive damage to the organ and more severe disease.
[9] Ischemia may occur as a result of vasospasm from shock, hypotension, thrombosis, or direct vascular compression of the hypophyseal artery from the enlarged pituitary gland itself.
[9][5][15] The presence of disseminated intravascular coagulation (i.e., in amniotic fluid embolism or HELLP syndrome) also appears to be a factor in its development.
[9] Typically an important clue that leads to a diagnosis of Sheehan's syndrome is identifying a deficiency in one or more of the hormones produced directly, or indirectly, by the pituitary gland.
If an MRI is conducted early enough in the disease process the pituitary may appear larger than normal, and show changes that are consistent with damage from lack of blood supply.
[9] In a study of 1,034 symptomatic adults, Sheehan's syndrome was found to be the sixth-most frequent etiology of growth hormone deficiency, being responsible for 3.1% of cases (versus 53.9% due to a pituitary tumor).
[9] A retrospective study in Turkey found that the prevalence of Sheehan's syndrome was directly proportional to the amount of at-home deliveries each decade.
Blood loss associated with episiotomy and forceps exacerbating blood loss when the placenta separates from the wall of the uterus, particularly in mothers with low blood pressure, even in obstetric setting, namely hospital, caused a more subtle Sheehan's syndrome of Growth Hormone, Anti-Duretic Hormone, ACTH deficiency, which may be life threatening if missed; PubMed.gov Sheehan's in modern times:a nationwide retrospective study Iceland 2011, where every mother gives birth in hospital, with full obstetric care available.