Sheehan's Syndrome

Sheehan's syndrome, also known as postpartum pituitary gland necrosis, occurs when the pituitary gland is damaged due to significant blood loss and hypovolaemic shock during or after childbirth. This damage leads to decreased functioning of the pituitary gland, resulting in hypopituitarism.

The pituitary gland, located in the brain's sella turcica, is an endocrine organ that produces and regulates various hormones, affecting numerous bodily functions such as growth, metabolism, menstruation, and lactation. Therefore, pituitary damage can have widespread effects.

Anatomy of normal pituitary gland and surrounding structures

Empty sella turcica on MRI as seen in severe cases of Sheehan's syndrome

Signs and Symptoms

The signs and symptoms of Sheehan's syndrome stem from pituitary damage, leading to reduced secretion of one or more hormones. Common signs include difficulties with or total absence of lactation (agalactorrhea), infrequent (oligomenorrhea) or absent menstrual cycles (amenorrhea), hot flashes, decreased libido, and breast involution. Thyroid disorder symptoms may include fatigue, cold intolerance, constipation, weight gain, hair loss, and slowed thinking, heart rate, and blood pressure.

Adrenal insufficiency may present acutely or chronically. Chronic adrenal insufficiency resembles Addison's disease, with symptoms such as fatigue, weight loss, hypoglycaemia, anaemia, and hyponatraemia. Acute adrenal crisis can be life-threatening, with hypoglycaemia, hypotension, weakness, fatigue, and seizures.

Growth hormone deficiency often manifests as low energy, body aches, and subtle wrinkling of the skin around the eyes or mouth. Anti-diuretic hormone deficiency may cause increased thirst, excessive urination, headache, and fatigue.

Causes

Sheehan's syndrome is primarily caused by excessive blood loss post-delivery, leading to pituitary damage. The pituitary gland enlarges during pregnancy to meet increased hormonal demands, making it more vulnerable to injury from hypovolaemic shock. Although typically linked to childbirth, Sheehan's syndrome can also occur due to massive haemorrhage from non-obstetrical causes.

Predisposing factors include disseminated blood coagulation, hypotension, small sella turcica size, and pre-existing hypercoagulable disorders.

Pathophysiology

Sheehan's syndrome arises from compounded factors leading to pituitary ischaemia and necrosis. The anterior pituitary, supplied by a low-pressure portal venous system, is more susceptible to damage. The gland's enlargement during pregnancy, combined with compromised blood supply, results in ischaemia. Factors like vasospasm from shock, hypotension, thrombosis, or direct vascular compression from the enlarged pituitary contribute to the condition. Disseminated intravascular coagulation further exacerbates the risk.

Diagnosis

Diagnosis involves identifying deficiencies in hormones produced by the pituitary gland through hormonal assays measuring levels of T4, TSH, oestrogen, gonadotropin, cortisol, and ACTH. Stimulation tests may be conducted if hormone levels are borderline. MRI is instrumental in diagnosing Sheehan's syndrome, revealing structural damage to the pituitary, which may appear enlarged early in the disease process and shrink later, leaving a partially or totally empty sella turcica.

Treatment

Treatment focuses on hormone replacement therapy tailored by an endocrinologist. Glucocorticoids are administered to address or prevent adrenal crises. Hormone replacement is very important for reducing the morbidity and mortality associated with Sheehan's syndrome.

Epidemiology

The prevalence of Sheehan's syndrome varies globally, being more common in developing countries. In the UK, only 1.4% of hypopituitarism patients were diagnosed with Sheehan's syndrome in 2001. The WHO estimated that 3 million women were affected worldwide in 1996. A study found Sheehan's syndrome to be the sixth-most frequent cause of growth hormone deficiency, with 3.1% of cases attributed to it.

History

The syndrome was first described by British pathologist Harold Leeming Sheehan in 1937, highlighting the association with postpartum haemorrhage. Sheehan's research distinguished Sheehan's syndrome from Simmonds' disease, noting the significant role of haemorrhaging in its development. In 1939, Sheehan further established the relationship between postpartum necrosis and Simmonds' disease.

Society and Culture

Sheehan's syndrome is rare in the developed world but remains prevalent in developing countries. The prevalence is linked to the rate of at-home deliveries. Improved obstetric techniques and hospital deliveries have reduced its incidence in developed countries, although it continues to affect women globally.

Research

The role of autoimmunity in Sheehan's syndrome is uncertain. Some cases have identified anti-pituitary and anti-hypothalamus antibodies in patients, but their exact role in the syndrome's development remains unclear.

Self-assessment MCQs (single best answer)

What is Sheehan's syndrome primarily caused by?

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Which gland is directly affected by Sheehan's syndrome?

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Which hormone deficiency is NOT commonly associated with Sheehan's syndrome?

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What imaging technique is essential for diagnosing Sheehan's syndrome?

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Which of the following is a common symptom of Sheehan's syndrome?

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Which of the following is NOT a predisposing factor for Sheehan's syndrome?

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What is the primary treatment approach for Sheehan's syndrome?

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Which of the following is a sign of adrenal insufficiency in Sheehan's syndrome?

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Who first described Sheehan's syndrome?

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In which countries is Sheehan's syndrome more commonly found?

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