Sheehan's syndrome (SS) occurs after massive hemorrhage or hypotension, during parturition or in the postnatal period, which causes necrosis of the pituitary gland and subsequent pituitary hormone deficiency.
The presentations of SS arise from pituitary injury leading to a diminished levels of one or more hormones secreted by the pituitary gland, such as prolactin, ADH, thyroid stimulating hormone (TSH) and cortisol  . Women with SS most commonly present with difficulty or inability to lactate (agalactorrhea). After delivery, if the menstrual cycle doesn’t return (amenorrhea) or is very light (oligomenorrhea), this may also be a sign of SS. Milder symptoms may go unnoticed in patients for years: fatigue, constipation, hair loss, bradycardia, hypotension and cold intolerance, which are all associated with hypothyroidism, may indicate SS. Due to the reliance of the adrenal gland on hormones produced by the pituitary gland, patients may also experience symptoms of adrenal deficiency, which is usually due to decreased circulating cortisol, causing anemia, low blood glucose and sodium, fatigue and weight loss. Furthermore, since cortisol is important for maintaining homeostasis, especially during stress, patients may experience attacks during high stress events, such as surgery or infection, leading to symptoms that correspond to an Addison crisis, which may be life threatening and should be treated immediately. Rarely, acute SS may occur following delivery and is primarily associated with hyponatremia. Loss of hormones is SS may follow a general pattern that starts with GH, followed by FSH, LH, ACTH and finally TSH.
Symptoms of SS vary widely, depending on which pituitary hormone is deficient, making diagnosis challenging. Women who present with symptoms possibly related to hypopituitarism and previously experienced hemorrhage during delivery are often diagnosed with SS. Specific symptoms may include dizziness, fatigue, weakness or hypoglycemia in women with ACTH deficiency, fatigue and decreased muscle mass and quality of life in women with GH deficiency and decreased libido, no or light menstrual cycle and hot flashes in women with FSH or LH deficiency. The hypopituitarism associated with SS often causes secondary hypothyroidism which is difficult to discern from primary hypothyroidism and leads to low levels of T3 and t$ hormones.
Women with SS that experience panhypopituitarism will have low levels of corticotropin, LH, thyrotropin, cortisol and thyroxine. To detect a partial hormone deficiency, stimulation tests are needed (metyrapone test and insulin hypoglycemia test). SS is suspected in mothers with low thyroid hormone and cortisol levels along with hyponatremia, especially if patients’ hormone levels are unchanged following insulin hypoglycemia tests.
Although radiographic imaging of the pituitary gland provides little help early on in SS disease progression, a smaller sella turcica may be observed in women in the more advanced stages of SS.
SS is addressed with the primary aim of replacing hormone deficiencies. If left untreated, the hormone imbalance associated with SS can be life threatening   . SS patients who have developed hypoadrenalism and hypothyroidism should be treated first with glucocorticoid replacement therapy before addressing thyroid deficiencies. Hormone replacement therapy is recommended for hypogonadism and GH deficiency. GH replacement must be individualized, started with low doses, tapered upward and closely monitored, so GH and insulin-like growth factor 1 levels remain within appropriate range. Body composition and cardiovascular risk should be considered with GH replacement therapy. Desmopressin should be administered to patients with diabetes insipidus. Patients hoping for a pregnancy should consult a fertility specialist.
SS is effectively treated with early diagnosis and care posing only a slight health risk for patients in developed countries. If untreated, SS is a life threatening condition.
SS arises from massive hemorrhage, vasospasm, compression of hypophyseal arteries and thrombosis during delivery that causes necrosis of the pituitary gland and subsequent hypopituitarism. The precise pathophysiology and etiology of SS remain unclear and the disease is rarely observed in developed countries because of optimal obstetrical care. However, SS is one of the leading sources of growth hormone (GH) deficiency in patients with GH-deficiency  .
SS prevalence is unclear due to the low number of diagnosed cases. One small study investigating causes of GH-deficiency indicated that SS was responsible for causing 3.1% of cases, rendering it the sixth most common cause of GH-deficiency. In that study, the most common cause of GH-deficiency was found to be pituitary cancer which was responsible for 53.9% of cases  .
The pituitary gland is particularly sensitive to ischemia during pregnancy and delivery due to 1) hyperplasia and hypertrophy of the lactotrophic cells in the anterior pituitary gland and 2) decreased portal pressure. Therefore, hypotension or a severe hemorrhage occurring during childbirth or in the period immediately after, will likely cause ischemia-induced necrosis of the anterior pituitary gland. The posterior pituitary remains unaffected because of the blood received from arterial vessels.
Signs and symptoms of SS arise from a deficiency in the circulation of one or more hormones secreted or induced by the pituitary gland, which include prolactin, ADH, thyroid stimulating hormone (TSH), cortisol, GH, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and adrenocorticotropic hormone (ACTH).
Prolactin deficiency results in inability to lactate, ADH deficiency may cause central diabetes insipidus, TSH deficiency can lead to hypothyroidism and low cortisol can cause mental ailments among other things. It is due to the diversity of symptoms that may arise in SS, that this condition is classified as a syndrome.
Sheehan's syndrome (SS) is associated with reduced pituitary hormone secretions (hypopituitarism) which stems from the necrosis of the pituitary gland that is caused by massive postpartum hemorrhage, vasospasm, compression of hypophyseal arteries and thrombosis. The necrotic pituitary gland will display impaired function, atrophy and scarring. During delivery, the pituitary gland has a heightened sensitivity to ischemia due to its larger size and the presence of circulating vasoconstrictors may cause vasospasm and low portal pressure. Patients most commonly present with breast involution and prolactin deficiency, which prevents lactation, followed by the failure to re-establish menstruation and the inability to regrow pubic and axillary hair. Overtime, hypothyroidism may cause fatigue, malaise, joint aches, anorexia, decreased skin pigmentation, mental disturbances (with or without psychosis) and decreased insulin dependence in women with type 1 diabetes. In rare cases women with SS that experience stress may develop acute adrenal crises and hypotension which may be lethal.
The pathogenesis of SS is diverse and may involve pituitary gland enlargement, low pressure regional perfusion, autoimmunity and disseminated intravascular coagulation. One out of three women with postpartum hemorrhage may experience various levels of hypopituitarism and, although symptoms rarely arise, many patients show diminished neurohypophyseal function when tested. In developing and underdeveloped countries SS is the most common cause of hypopituitarism, but due to advanced obstetrical care, SS and hypopituitarism are rare in developed countries. Some suggested predisposing factors may include the presence of a previously unknown pituitary mass, smaller and more rigid sella turcica, type 1 diabetes and preexisting vascular disease.
Postmortem analysis often reveals neurohypophyseal scarring along with paraventricular nuclei and surpraoptic scarring, locations which secrete antidiuretic hormone (ADH). A lack of ADH may cause central diabetes insipidus (DI)   .
Sheehan syndrome (SS) is a rare disorder, caused by severe bleeding of women during child delivery. The pituitary gland of pregnant women is particularly sensitive to decreased blood flow and extensive hemorrhage causes large areas of the pituitary gland to die, leading to a decreased hormone production. The pituitary gland produces a variety of hormones including those that stimulate milk production, growth, the adrenal gland, the thyroid gland and regulate menstruation. Women pregnant with multiple babies or those who have issues with their placenta have a higher risk of having severe hemorrhages during delivery and therefore a higher risk of developing SS.
The symptoms that accompany SS may appear right away or after several years and include inadequate breast milk production, low blood pressure, fatigue, hair loss (axillary and pubic) and absent or light menstrual cycle. There are a number of blood tests that can be done to assess the levels of circulating hormones in your blood. Imaging may be performed to assess the pituitary gland and exclude other causes.
Hormone replacement therapy, including estrogen and progesterone will be given until 48 to 55 years of age, and thyroid and adrenal hormone supplements will be given indefinitely to treat SS. With early diagnosis and modern treatments the prognosis is good, however, in underdeveloped and developing countries women often go undiagnosed and receive suboptimal treatments leading to severe complications and even death. Proper care during delivery may reduce the risk of severe bleeding and SS.