What is a thyroid storm (thyrotoxic crisis)?

From the Guidelines

Thyroid storm is a life-threatening medical emergency that requires immediate hospitalization and aggressive management to prevent morbidity and mortality. Thyroid storm is a rare but severe condition caused by extreme overactivity of the thyroid gland, typically occurring in patients with untreated or undertreated hyperthyroidism who experience a triggering event such as infection, trauma, surgery, or stress. Symptoms include extremely high fever, rapid heart rate, high blood pressure, agitation, confusion, delirium, severe nausea, vomiting, diarrhea, and in severe cases, heart failure, coma, or death.

Key Characteristics and Treatment

• The condition is characterized by a massive release of thyroid hormones, which dramatically increases metabolism throughout the body, causing multi-organ dysfunction.
• Treatment requires a multi-faceted approach, including beta-blockers like propranolol to control heart rate, as supported by recent studies 1.
• Antithyroid medications such as propylthiouracil (PTU) or methimazole are used to block thyroid hormone production.
• Iodine solutions, typically SSKI or Lugol's solution, are given 1 hour after antithyroid drugs to block hormone release.
• Corticosteroids like hydrocortisone are used to reduce conversion of T4 to T3.
• Supportive care, including cooling measures, IV fluids, and treatment of any underlying trigger, is also essential.

Management and Outcomes

Without prompt treatment, mortality rates can reach 10-30%, making rapid recognition and aggressive management essential, as highlighted in guidelines for managing patients with atrial fibrillation 1. The use of beta-blockers, particularly propranolol, is crucial in managing thyroid storm, as it not only controls heart rate but also inhibits the peripheral conversion of T4 to T3, as discussed in recent studies on individualized beta-blocker treatment 1.

From the FDA Drug Label

Propylthiouracil inhibits the conversion of thyroxine to triiodothyronine in peripheral tissues and may therefore be an effective treatment for thyroid storm. Beta-adrenergic blockade may mask certain clinical signs of hyperthyroidism. Therefore, abrupt withdrawal of propranolol may be followed by an exacerbation of symptoms of hyperthyroidism, including thyroid storm.

Thyroid storm is a severe and life-threatening exacerbation of hyperthyroidism symptoms. It can be precipitated by the abrupt withdrawal of beta-adrenergic blockade therapy, such as propranolol. Propylthiouracil may be an effective treatment for thyroid storm due to its ability to inhibit the conversion of thyroxine to triiodothyronine in peripheral tissues 2 3.

From the Research

Definition and Incidence of Thyroid Storm

• Thyroid storm, also known as thyrotoxic crisis, is a rare but life-threatening condition that requires immediate treatment, preferably in an intensive care unit 4.
• The incidence of thyroid storm is about 1-2% among patients with overt hyperthyroidism, and it is three to five times more common in women than in men 4.
• The overall mortality rate of thyroid storm is 10-20%, and any delay in therapy can increase the mortality rate to 75% 4.

Pathogenesis and Diagnosis

• The pathogenesis of thyroid storm is not fully understood, but an increased sensitivity to catecholamines appears to be an important mechanism 4.
• The diagnosis of thyroid storm is made entirely on clinical findings, and there is no difference in thyroid hormone levels between patients with "uncomplicated" thyrotoxicosis and those undergoing a thyroid storm 4.
• A scoring system based on clinical criteria is used to diagnose thyroid storm, as no laboratory abnormalities are specific to the condition 5.

Treatment and Management

• Medical treatment of thyroid storm is based on three principles: counteracting the peripheral effects of thyroid hormones, inhibition of thyroid hormone synthesis, and treatment of systemic complications 4.
• Treatment should be initiated promptly, targeting all steps of thyroid hormone formation, release, and action 5.
• Patients who fail medical therapy may require therapeutic plasma exchange or thyroidectomy 5.
• Rectal administration of iodide and propylthiouracil can be an effective alternative to parenteral sodium iodide for patients with upper gastrointestinal tract dysfunction 6.
• Extra-corporeal treatments, such as therapeutic plasma exchange and veno-arterial extra-corporeal membrane oxygenation, may be used in severe cases of thyroid storm 7.