Sheehan's syndrome overview

# Overview
Sheehan's syndrome is a life-threatening complication of severe postpartum hemorrhage (PPH) that results in mild to severe maternal hypopituitarism. Sheehan's syndrome is less prevalent in developed countries, but it is still one of the most common causes of hypopituitarism in underdeveloped and developing countries. During pregnancy, enlarged size of the pituitary gland and decreased blood supply due to any cause can result in ischemic necrosis of pituitary gland. Severe PPH, glandular hypertrophy and hyperplasia, smaller sella size, autoimmunity, and disseminated vascular coagulation (DIC) are thought to play an important role in the pathogenesis of Sheehan's syndrome. The most common causes of Sheehan's syndrome include massive hemorrhage during parturition, vascular compression, and vascular occlusion. Sheehan's syndrome needs to be differentiated from diseases causing hypopituitarism and other diseases like lymphocytic hypophysitis, pituitary apoplexy, hypothyroidism, addison's disease, empty sella syndrome, hypogonadotropic hypogonadism, simmond's disease, hypoprolactinemia, and menopause. Risk factors for Sheehan's syndrome include pregnancy, severe/massive PPH, pituitary mass, pre-existing vascular diseases, smaller and rigid sella, traumatic delivery, multiple gestations, placental abnormalities, and type 1 diabetes. If left untreated, Sheehan's syndrome can lead to panhypopituitarism and empty sella syndrome. Common complications of Sheehan's syndrome include adrenal crisis, hypotension, hypothyroidism, and hypopituitarism. Prognosis is generally excellent, providing early diagnosis and management may result in complete reversal of symptoms. Diagnosis of Sheehan's syndrome is made on clinical basis with a recent/remote history of traumatic delivery or delivery complicated by hypotension. The most common presentations include postpartum lactation failure, amenorrhea, loss of sexual hair, fatigue, anorexia, and weight loss. Clinical features depend on the severity of hypopituitarism that results from Sheehan's syndrome. Almost all the patients have growth hormone (GH), prolactin, and gonadotropin deficiency; and the majority of the patients have ACTH and TSH deficiency. Laboratory evaluation in patients with Sheehan's syndrome gives a picture of partial or panhypopituitarism. Other laboratory findings include hyponatremia, hypokalemia, hypocalcemia, hypomagnesemia, hypophosphatemia, anemia, pancytopenia, eosinophilia, hypoalbuminemia, low fasting plasma glucose, and decreased levels of anterior pituitary hormones (free thyroxine, estradiol, and cortisol levels). The most sensitive test is inadequate prolactin and gonadotropin response to stimulation. ECG findings associated with Sheehan's syndrome include QT interval prolongation, type-1 Brugada-like ECG pattern (due to adrenal crisis), findings suggestive of cardiac tamponade (sinus tachycardia, low voltage QRS, and electrical alternans), and dilated cardiomyopathy. CT scan findings in case of acute Sheehan's syndrome may show non-hemorrhagic pituitary gland enlargement, while chronic presentation may show an empty sella or decreased sella volume. Findings on MRI suggestive of Sheehan's syndrome include decreased sella volume, empty sella, pituitary remnant tissue or CSF in the sella. The treatment of Sheehan's syndrome involves appropriate hormone replacement therapy, which must be taken for the rest of the patient's life, results in significant improvement and reversal of not only the physical symptoms, but also the psychological symptoms.

# Historical Perspective
Sheehan's syndrome was first discovered by Leon Konrad Glinski about a century ago and it was named after Harold Sheehan (1900-1988).

# Classification
Sheehan's syndrome may be classified based on the onset or presentation of symptoms and the degree of glandular damage. Sheehan's syndrome may be classified into acute and chronic subtypes based on the time period after delivery and also extent of glandular damage.

# Pathophysiology
It is believed that Sheehan's syndrome is the result of ischemic necrosis of pituitary gland, due to pituitary gland enlargement during parturition that is precipitated by hypotension due to massive hemorrhage. Apart from pituitary gland enlargement during and before parturition, vasospasm, generalized Schwartzman phenomenon, thrombosis and compression of the hypophyseal arteries, autoimmunity, DIC, and smaller size of sella play a contributing role in pathogenesis of Sheehan's syndrome. Occlusion and other vascular anomalies of the hypophyseal portal system can also complicate the exchange of hormones between the hypothalamus and the pituitary gland, leading to hypopituitarism. Sheehan's syndrome may result in mild to severe pituitary dysfunction (partial or panhypopituitarism), which is identified with growth hormone (GH), thyroid hormone, glucocorticoid, gonadotropins, and prolactin hormone deficiencies, and manifests as a wide spectrum of presentation. Usually, GH deficiency is the earliest one to develop.

# Causes
Common causes of Sheehan's syndrome include massive hemorrhage, hypotension during pregnancy, vascular compression, and vascular occlusion (thrombosis, DIC). Less common causes are vascular insufficiency due to coronary artery bypass grafting (CABG) in older patients and snake bites (Russell's viper bites).

# Differentiating Sheehan's syndrome from Other Diseases
Sheehan's syndrome must be differentiated from lymphocytic hypophysitis, pituitary apoplexy, hypothyroidism, Addison's disease, panhypopituitarism, empty sella syndrome, hypogonadotropic hypogonadism, Simmond's disease, hypoprolactinemia, and menopause on the basis of hypo-functioning of the pituitary.

# Epidemiology and Demographics
The incidence of Sheehan's syndrome is difficult to assess. It was found to be the 6th most common cause of growth hormone (GH) deficiency with an incidence of 3.1% of cases. In 2009, the prevalence of Sheehan's syndrome was estimated to be 5.1 per 100,000 women. Sheehan's syndrome is less prevalent in developed countries due to better obstetrical care and maternal health awareness. Sheehan's syndrome is one of the most common causes of hypopituitarism in developing countries.

# Risk Factors
Common risk factors in the development of Sheehan's syndrome include pregnancy, severe/massive postpartum hemorrhage (PPH), pituitary mass, pre-existing vascular diseases, autoimmunity, DIC, smaller and rigid sella, and traumatic delivery.

# Screening
There is insufficient evidence to recommend routine screening for Sheehan's syndrome.

# Natural History, Complications, and Prognosis
If left untreated, Sheehan's syndrome leads to hypopituitarism and empty sella syndrome. Common complications are adrenal crisis, hypotension, hypothyroidism, and hypopituitarism. Prognosis is generally excellent; early diagnosis and management often results in a complete reversal of symptoms.

# Diagnosis
Diagnosis of Sheehan's syndrome is made on clinical basis with a recent or remote history of traumatic delivery or delivery complicated by hypotension. Diagnosis is mostly clinical but detailed medical history, measurement of pituitary hormone levels in blood, pituitary hormone stimulation tests and imaging (MRI preferred on CT) studies can help in making the diagnosis.

## History and Symptoms
The most common symptoms of Sheehan's sydrome are agalactorrhea and failure to resume menstruation after parturition. Common symptoms are hot flashes, decreased pubic or axillary hair, hypotension, hypoglycemia, features of hypothyroidism, hypoadrenalism, and hypogonadism.

## Physical Examination
Patients with Sheehan's syndrome usually appear fatigued and lethargic. Physical examination is remarkable for bradycardia, hypotension, pallor, and signs suggestive of respective pituitary hormonal deficiency.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of Sheehan's syndrome include hyponatremia, hypokalemia, hypocalcemia, hypomagnesemia, hypophosphatemia, anemia, pancytopenia, eosinophilia, hypoalbuminemia and low fasting plasma glucose.

## Electrocardiogram
Electrocardiogram (ECG) findings associated with Sheehan's syndrome may include QT interval prolongation, type-1 Brugada-like ECG pattern (due to adrenal crisis), or findings suggestive of cardiac tamponade or dilated cardiomyopathy.

## X-ray
There are no x-ray findings associated with Sheehan's syndrome.

## CT scan
CT scans in patients with Sheehan's syndrome shows non-hemorrhagic pituitary gland enlargement in acute cases while chronic cases present as an empty sella or decreased sella volume.

## MRI
Findings on MRI suggestive of Sheehan's syndrome are decreased sella volume, empty sella, pituitary remnant tissue, or cerebrospinal fluid (CSF) in sella.

## Ultrasound and Echocardiography
Echocardiography findings associated with Sheehan's syndrome may include reversible dilated cardiomyopathy and pericardial effusion.

## Other Imaging Findings
There are no other imaging findings associated with Sheehan's syndrome.

## Other Diagnostic Studies
Surgical intervention may be considered when there is emergency presentation, such as pituitary apoplexy or subarachnoid hemorrhage causing Sheehan's syndrome to prevent hypopituitarism.

# Treatment

## Medical Therapy
The treatment of Sheehan's syndrome involves hormone replacement therapy, which generally results in complete recovery and reversal of symptoms.

## Surgery
Surgical intervention is not recommended for the management of Sheehan's syndrome.

## Primary Prevention
Effective measures for the primary prevention of Sheehan's syndrome include improved obstetrical care and perinatal monitoring, prevention of pregnancy related complications such as hypotension or hemorrhage, maternal awareness about risk factors of Sheehan's syndrome, and post-puerperal follow up.

## Secondary Prevention
Effective measures for the secondary prevention of sheehan's syndrome are early diagnosis and treatment to prevent life-threatening complications, such as adrenal crisis and infertility. Other measures of secondary prevention include frequent prenatal visits and prevention of development of hypotension due to any reason.