Postpartum hypopituitarism (more commonly known as Sheehan syndrome) refers to the condition of decreased, impaired, or lacking anterior pituitary function after a pregnancy.  

This condition is due to ischemic necrosis following excessive blood loss or postpartum hemorrhage at time of delivery. Damage to the pituitary gland can lead to dysfunction of the hypothalamic, pituitary, gonadal, and/or other hormonal axis. The degree of damage may be minimal or could lead to complete loss of all anterior pituitary hormones.   

Incidence is rare in industrialized nations due to prompt access to blood transfusions and preventive maneuvers at the time of delivery. Risk factors for developing postpartum hypopituitarism include retained placenta, postpartum hemorrhage, multiparity, having a bleeding disorder, and any other factors that can lead to postpartum hemorrhage (eg, operative delivery, prolonged labor, infection, uterine atony).

If occurring acutely at the time of hemorrhage, patients will present with hypotension, tachycardia, and hypoglycemia. Unfortunately, these are also seen as manifestations of acute blood loss anemia from the hemorrhage and, thus, the diagnosis may be delayed. There is usually a moderately large lag time between hemorrhage and onset of symptoms; it may be years between the event and symptoms.

Patients may present with a complaint of amenorrhea dating back to the time of their delivery or shortly thereafter. They may also note they had difficulty with or absence of lactation. Other supporting symptoms include features related to hypothyroidism (eg, fatigue, weight gain, hair loss) or other decreased hormones (eg, hot flashes. hypotension, hypoglycemia). Some patients will be asymptomatic. Very rarely, patients will present with adrenal crisis; this can be a sudden-onset life-threatening emergency that must be immediately addressed.