You’ve heard of rainstorms and snowstorms and even sandstorms… but have you ever heard of a thyroid storm? Like a severe weather system, a thyroid storm can develop quite suddenly—and it can have deadly consequences, particularly if it is not recognized immediately and treated aggressively, according to Rebecca S. Bahn, MD, an endocrinologist at Mayo Clinic and task force chair for the American Thyroid Association. Though a thyroid storm is fairly rare, its high mortality rate makes it vital to understand what the condition is and whether you or someone you love might be at risk.

The thyroid gland at the base of the neck produces hormones called T3 and T4 that regulate metabolism, or the way the body’s cells use energy. For various reasons, in some people, the thyroid produces or releases too much T3 and T4, a condition called hyperthyroidism. Symptoms include rapid heart rate, weight loss, nervousness, increased sweating and irregular menstrual periods.

An estimated two million Americans have hyperthyroidism, though many are undiagnosed… and according to the American Association of Clinical Endocrinologists, women are five to 10 times more likely than men to develop the condition. People with hyperthyroidism are the ones vulnerable to having a thyroid storm—among that group, approximately 1% to 2% will experience this crisis at some point, Dr. Bahn said.

A thyroid storm can occur when, due to any of various triggers (outlined below), patients with already high thyroid hormone levels become more sensitive to the accompanying outpouring of catecholamines (stress-response hormones). This creates an acute hypermetabolic state (in which the metabolic rate is excessive) that can lead to extremely high fever, very rapid and irregular heartbeat, congestive heart failure and buildup of fluid in the lungs. “Death can occur in some 90% of patients in whom the thyroid storm diagnosis is missed. With early diagnosis and treatment, the mortality rate declines to about 20%,” Dr. Bahn said.

Thyroid storm can develop when a hyperthyroid patient…

  • Is not being adequately treated for hyperthyroidism.
  • Stops taking his or her propylthiouracil or methimazole (Tapazole) antithyroid medication.
  • Receives radioactive iodine therapy for treatment of hyperthyroidism (though this is rare).
  • Has uncontrolled diabetes.
  • Undergoes major surgery.
  • Experiences medical trauma.
  • Has a serious infection, especially of the lung.
  • Suffers a heart attack.
  • Has a severe reaction to a medication.
  • Goes through complicated childbirth.

Patients with hyperthyroidism can lower their risk for a deadly storm by never altering or halting their antithyroid medication without a doctor’s OK and by refraining from strenuous exercise until their hyperthyroidism is under control.

MAKING IT THROUGH THE STORM

If a thyroid storm does develop, survival requires immediate medical attention, Dr. Bahn emphasized—so people who have hyperthyroidism (and their loved ones) must be on the lookout for the warning signs. The more of the following symptoms a person has, the more critical it is to get to a hospital emergency room. Watch for the sudden appearance of…

  • High fever
  • Confusion, disorientation, agitation, anxiety
  • Nausea, vomiting, abdominal pain, diarrhea
  • Rapid or irregular heartbeat
  • Chest pain
  • Shortness of breath
  • Heavy sweating, flushing
  • Extreme weakness, fatigue
  • Tremor, seizure

Treatment advances: In the past, a thyroid storm was virtually always fatal. “But in the last 20 to 30 years, we’ve developed good treatments for it. We basically hit it from all directions,” Dr. Bahn said.

Typically, a patient receives an arsenal of drugs, including various intravenous medications to block thyroid hormone production… potassium iodide to prevent hormone release… beta-blockers to control heart rate and halt the action of the thyroid hormones on the body’s cells… and fever reducers to bring down body temperature. Intravenous fluids, supplemental oxygen and cooling blankets may be used. In addition, measures are taken to control any underlying condition that contributed to the thyroid storm.

An intensive care unit stay of several days usually is necessary. Then the patient follows up with her doctor in the weeks after the episode to make sure that her hyperthyroidism is very well controlled henceforth—so that no repeat thyroid storm threatens in the future.