All About Thyroid Storm

Thyroid storm is caused severely elevated levels of thyroid hormone availability in the blood (thyrotoxicosis). While hyperthyroidism causes chronically high levels of thyroid hormone, hyperthyroidism alone does not usually cause levels sever enough to cause thyroid storm.  Although thyroid storm is rare, the most common causes of thyroid storm occur in people with unregulated hyperthyroidism that undergo surgery, post-partum, infection, trauma, contrast dyes containing iodine.

What Happens During Thyroid Storm?

Thyroid storm is a rare complication that is life-threatening due to exaggerated side-effects of hyperthyroidism.

  • Rapid heart rate (tachycardia)
  • Fever – greater than 102 degrees Fahrenheit
  • Agitation
  • Coma
  • Delirium
  • Psychosis
  • Stupor
  • Abdominal pain
  • Diarrhea
  • Nausea
  • Vomiting

Thyroid storm can cause congestive heart failure leading to pulmonary edema (fluid in the lungs). Both heart arrhythmias (irregular heart rhythms) and pulmonary edema are the main cause of death in thyroid storm.

How Is Thyroid Storm Diagnosed?

While laboratory analysis of thyroid stimulating hormone (TSH), Free thyroxine (T4) and Free triiodothyronine (T3) can be used to help diagnose thyroid storm, it is more a a clinical assessment diagnosis by identifying the symptoms listed above in the presence of depressed TSH and an elevated Free T4 count. Other lab analysis may include complete blood cell count, liver function tests, and electrolyte panels (for blood sugar and calcium levels).

The lab results are less important than signs of hyperthyroidism and suspicion of thyroid storm. Treatment should be initiated as soon as possible without receiving the results of the labs under direct supervision of a physician. Treatment likely will occur in an intensive care unit.

How Is Thyroid Storm Treated?

Treatment of thyroid storm is very goal oriented. Primary goals include blocking the creation and release of TSH, halting the conversion of T4 to T3, controlling heart arrhythmias, and other comfort measures for other less life-threatening symptoms.

If ICU monitoring is not necessary, initial therapy should include methimazole. This therapy is generally the preferred initial therapy if severe hyperthyroidism is the concern, because it is less toxic to the liver and can generally lead to more normalized levels faster. If ICU monitoring is required due to life-threatening thyroid storm, propylthiouracil (PTU) is suggested. Prior to leaving the ICU, methimazole will be used to replace PTU therapy. If methimazole or PTU is unable to be used, stabilization of symptoms and surgery to remove the thyroid is recommended.

A glucocorticoid like dexamethasone will be started to help prevent the conversion of T4 to T3. T3 is important thyroid hormone that helps regulate the body’s metabolic rate. Cholestyramine (a bile acid sequestrant) can be useful  in recycling thyroid hormones, removing them from circulation.

In order to control a fast heart rate (> 140 beats per minute) and an irregular heart rhythms, a beta blocker will likely be started. This will help prevent complications of congestive heart failure and subsequent pulmonary edema.

The rest of the symptoms are more an issue of discomfort. Some may be quite severe and require treatment. Other therapies would include controlling the temperature by using antipyretics like Tylenol or cooling blankets, anti-nausea medications and IV fluids (to replace fluid loss through vomiting and diarrhea).

Thyroid storm is rare, however very life-threatening. If you have hyperthyroidism and exhibit the symptoms listed above, you should seek immediate attention in an emergency department.


Ross, D.S., Cooper, D.S., & Mulder, J.E. (2015). Thyroid Storm. Accessed on June 30, 2015 from

U.S. National Library of Medicine. (2014). Thyroid Storm. Accessed on June 30, 2015 from

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