Thyroid storm

Thyroid storm
Other names	Thyrotoxic crisis
Specialty	Endocrinology
Differential diagnosis	Sepsis, infectious disease[1]
Prognosis	8-25% mortality with treatment; 80-100% mortality if untreated

Thyroid storm is a rare but severe and life-threatening complication of hyperthyroidism. It occurs when an overactive thyroid leads to hypermetabolism, which can cause death from cardiac arrest or multiple organ failure.^[2]

It is characterized by a high fever (temperatures often above 40 °C / 104 °F), fast and often irregular heart beat, elevated blood pressure, vomiting, diarrhea, and agitation. Hypertension with a wide pulse pressure occurs in early to mid crisis, with hypotension accompanying shock occurring in the late stage.^[3] Heart failure and heart attack may occur. Death may occur despite treatment.^[4] Most episodes occur either in those with known hyperthyroidism whose treatment has stopped or become ineffective, or in those with untreated mild hyperthyroidism who have developed an intercurrent illness (such as an infection).^[4]

The primary treatment of thyroid storm is with inorganic iodine and antithyroid drugs (propylthiouracil or methimazole) to reduce synthesis and release of thyroid hormone. Temperature control and intravenous fluids are also mainstays of management. Beta blockers are often used to reduce the effects of thyroid hormone.^[5] Patients often require admission to the intensive care unit.^[6]

As a life-threatening medical emergency, thyroid storm has a mortality rate of up to 25% despite treatment.^[1][7] Without treatment, the condition is typically fatal, with a mortality rate of 80-100%.^[8] Historically, the condition was considered untreatable, with hospital mortality rates approaching 100%.^[9][10]