to rev up the production of certain hormones associated with pregnancy. This higher metabolic demand, in turn, leads to higher demand for blood flow. 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. Although the vast majority of cases of Sheehan's syndrome occur in the setting of massive blood loss, cases have been documented of acute Sheehan's syndrome occurring with blood loss volumes that are not considered "massive". Some possible predisposing factors to Sheehan’s syndrome may include: disseminated blood coagulation (DIC), hypotension, small sella turcica size, and blood clots from a pre-existing hypercoagulable disorder. Atony of the uterus is a leading cause of post-partum hemorrhage, therefore uterine atony could induce Sheehan’s syndrome. Pathophysiology This syndrome seems to arise when certain factors compound each other to cause pituitary injury. The physiologic enlargement of the pituitary gland in conjunction with an interference in its blood supply ultimately result in pituitary ischemia and necrosis. 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. Other hormone-secreting cells of the pituitary undergo rapid growth in pregnant women as well, which contribute to the gland's enlargement. The anterior pituitary is supplied by a low pressure portal venous system. The anterior pituitary is more commonly affected in Sheehan's syndrome because of the structure of the portal venous system. Posterior pituitary involvement leading to central diabetes insipidus is much rarer, and typically reflects more extensive damage to the organ and more severe disease. It has been suggested that the arrangement of the pituitary's blood supply contribute to its susceptibility for injury. "The highly vascularized pituitary tissue involves one of the most rapid blood flow in the human body and probably, therefore, has a tendency to infarction because even small degrees of change in the pituitary intravascular pressure cause an arrest of blood flow". 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. The presence of disseminated intravascular coagulation (i.e., in amniotic fluid embolism or HELLP syndrome) also appears to be a factor in its development. Diagnosis Typically an important clue that leads to a diagnosis of Sheehan's syndrome is identifying a deficiency in one or more of the hormones