Diseases & Conditions A - Z
powered by Talix

Thyroid Storm

What is thyroid storm?

Thyroid storm is a life-threatening health condition that is associated with untreated or undertreated hyperthyroidism. During thyroid storm, an individual’s heart rate, blood pressure, and body temperature can soar to dangerously high levels. Without prompt, aggressive treatment, thyroid storm is often fatal.

The thyroid is a small, butterfly-shaped gland located in the middle of your lower neck. The two essential thyroid hormones produced by the thyroid are triiodothyronine (T3) and thyroxine (T4). These control the rate at which every cell in your body works (your metabolism). If you have hyperthyroidism, your thyroid is producing too much of these two hormones. This causes all of your cells to work too quickly. For example, your respiration rate and heart rate will be higher than they normally would. You may even speak far more quickly than you usually do.

Causes of thyroid storm

Thyroid storm is rare. It develops in people who have hyperthyroidism but aren’t receiving appropriate treatment. This condition is marked by the extreme overproduction of the two hormones produced by the thyroid gland. Not all people with hyperthyroidism will develop thyroid storm. Causes of this condition include:

  • severe undertreated hyperthyroidism
  • untreated overactive thyroid gland
  • infection associated with hyperthyroidism

People with hyperthyroidism may develop thyroid storm after experiencing one of the following:

Symptoms of thyroid storm

Symptoms of thyroid storm are similar to those of hyperthyroidism, but they are more sudden, severe, and extreme. The symptoms are often debilitating, which is why people with thyroid storm might not be able to seek care on their own. Common symptoms include:

Diagnosing thyroid storm

Individuals with hyperthyroidism who experience any symptoms of thyroid storm are typically admitted to the emergency room. If you suspect you or someone else has thyroid storm symptoms, call 911 immediately. People with thyroid storm generally exhibit an increased heart rate, as well as a high top blood pressure number (systolic blood pressure).

A doctor will measure your thyroid hormone levels with a blood test. Thyroid stimulating hormone (TSH) levels tend to be low in hyperthyroidism and thyroid storm. According to the American Association for Clinical Chemistry (AACC), normal values for TSH range from 0.4 to 4 mIU/L. T3 and T4 hormones are higher than normal in people with thyroid storm.


Thyroid storm develops abruptly and affects all the systems of your body. Treatment will begin as soon as thyroid storm is suspected — usually before lab results are ready. Antithyroid medication like propylthiouracil (also called PTU) or methimazole (Tapazole) will be given to reduce the production of these hormones by the thyroid.

Hyperthyroidism requires ongoing care. People with hyperthyroidism may be treated with radioactive iodine, which destroys the thyroid, or a course of drugs to suppress thyroid function temporarily. Pregnant women who have hyperthyroidism can’t be treated with radioactive iodine because it would harm the unborn child. In those cases, the woman’s thyroid would be removed surgically.

Patients should avoid taking iodine in lieu of medical treatment, as this can worsen the condition. If your thyroid is destroyed by radioactive iodine treatment or removed surgically, you will need to take synthetic thyroid hormone for the rest of your life.

Long-term outlook

Thyroid storm requires immediate, aggressive emergency medical attention. When left untreated, thyroid storm can cause congestive heart failure. Patients may also experience fluid-filled lungs. According to an article published in a German medical journal, the mortality rate for people with untreated thyroid storm is 75 percent.

The chances of surviving thyroid storm increase if you quickly seek medical care. Related complications may be lessened once your thyroid hormone levels are returned to the normal range (known as euthyroid).

Preventing thyroid storm

The most effective way to prevent the onset of thyroid storm is to keep up with your thyroid health plan. Take your medications properly. Keep all appointments with your doctor and follow through with blood work orders as needed.

Content licensed from:

Written by: Kristeen Moore
Medically reviewed on: Aug 03, 2015: Dr. Jeanne Morrison

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
Symptom Search
Enter your symptoms in our Symptom Checker to find out possible causes of your symptoms. Go.
Drug Interaction Checker
Enter any list of prescription drugs and see how they interact with each other and with other substances. Go.
Pill Identifier
Enter its color and shape information, and this tool helps you identify it. Go.
Drugs A-Z
Find information on drug interactions, side effects, and more. Go.