Pituitary Infarction

Infarction of the of the pituitary gland has been long recognized to cause loss of all pituitary function. The most common situations occur around pregnancy

Sheehan's syndrome is description of a specific event of pituitary infarction (bleeding) that occurs due to post partum hemorrhage (PPH). PPH is an emergency situation in which there is excessive bleeding that makes a patient ill and results in low blood pressure. Usually this condition requires transfusion of several units of blood. This syndrome, if severe,  results in fatigue, weight loss, and inability of lactate in the first weeks after delivery.  Patients can lose all anterior pituitary hormone function and rarely vasopressin as well. 

Russell's viper snake pituitary infarction
Other rare causes of pituitary infarction include reduced blood flow that occurs during coronary artery bypass surgery in elderly patients and Russell's viper (snake) bits in southeast asia

Regardless of the cause, an endocrinologist can help in the management of low pituitary function.  

Zargar AH, Singh B, Laway BA, Masoodi SR, Wani AI, Bashir MI. Epidemiologic aspects of postpartum pituitary hypofunction (Sheehan's syndrome). Fertil Steril. 2005;84
Antonypillai CN, Wass JA, Warrell DA, Rajaratnam HN. Hypopituitarism following envenoming by Russell's vipers (Daboia siamensis and D. russelii) resembling Sheehan's syndrome: first case report from Sri Lanka, a review of the literature and recommendations for endocrine management. QJM. 2011;104(2):97