Thyroid storm

Thyroid storm or thyrotoxic crisis is a rare but severe and potentially life-threatening complication of hyperthyroidism (overactivity of the thyroid gland). It is characterized by a high fever (often above 40 °C/104 °F), fast and often irregular heart beat, vomiting, diarrhea and agitation. Heart failure may occur, and myocardial infarction is encountered. Death may occur despite treatment.^[1] Most episodes occur either in those with known hyperthyroidism whose treatment has been stopped or become ineffective, or in those with untreated mild hyperthyroidism who have developed an intercurrent illness (such as an infection).^[1]

The severity of hyperthyroidism, thyrotoxicosis and thyroid storm can be assessed with the Burch-Wartofsky score, first introduced in 1993.^[1][2] A score is derived from various clinical parameters (such as temperature, severity of agitation); a score below 25 excludes thyroid storm, 25–45 suggests impending storm, and above 45 is suggestive of thyroid storm.^[3]

Thyroid storm requires prompt treatment and hospitalization. Often, admission to the intensive care unit is needed.^[3] Inorganic iodide (ideally potassium iodide and not Lugol's iodine) and antithyroid drugs (propylthiouracil or methimazole) are used to reduce the release of thyroid hormone from the gland, and beta blockers (e.g. propranolol) to reduce the effect of circulating thyroid hormone on end organs.^[1][3] Corticosteroids, like dexamethasone, are used to prevent peripheral conversion of T4 to T3. In high fever, temperature control is achieved with paracetamol/acetaminophen, and frequently fluid replacement, mechanical ventilation and corticosteroids.^[3] Any suspected underlying cause is also addressed.^[1]

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