Signs of a Thyroid Storm—and How to Know If You’re At Risk

A thyroid storm can happen if hyperthyroidism—an excess of thyroid hormones—is uncontrolled, leading to potentially life-threatening increases in heart rate and body temperature, among other serious problems.

The thyroid does a lot for your body. The small gland, located at the front of your neck, produces thyroid hormone, which is crucial for controlling your body’s metabolism—everything from how fast your heart beats to how quickly you burn calories is determined by one little organ. That means that when it doesn’t function exactly as it should, things can get out of sync.

Your thyroid can be underactive (hypothyroidism) or overactive (hyperthyroidism) but the latter is more common, says Marilyn Tan, MD, chief of the Stanford Endocrine Clinic in Stanford, California. The main cause of hyperthyroidism is Graves’ disease, an autoimmune disease that damages the thyroid gland and impacts more women than men.

Hyperthyroidism can be controlled with medication, but if it goes uncontrolled for a long time, it can result in a medical emergency known as a thyroid storm.

What is a thyroid storm?

Thyroid storm is a condition that develops when the thyroid is so overactive that the levels of thyroid hormone in the blood becomes toxic. It’s a life-threatening condition that requires immediate medical treatment.

“Fortunately, it’s pretty uncommon,” says Anne R. Cappola, MD, professor of medicine in the division of diabetes, endocrinology and metabolism and a member of the Thyroid Center Treatment team at Penn Medicine in Philadelphia. It’s not well studied, but Dr. Cappola suggests that about five of every 100,000 hospitalized patients each year has thyroid storm.

It’s not something that you will just develop overnight without already having an overactive thyroid, says Dr. Tan. “Most of the time, people who do present with thyroid storm have had hyperthyroidism for quite some time.” While it is possible to be undiagnosed with hyperthyroidism and end up with dangerously high levels of thyroid hormone requiring immediate attention, it’s rare for thyroid storm to happen this way, says Dr. Cappola. Most people feel sick enough from normal hyperthyroidism that they seek medical attention before it turns to dangerous thyroid-storm levels.

The biggest risk factor

Thyroid storm can happen if hyperthyroidism goes uncontrolled for too long. “Most of the time, patients have known thyroid disease and stop taking medications,” says Dr. Cappola. “As long as you’re on some kind of anti-thyroid drug, it keeps you out of bad trouble. So generally, you would have to stop them altogether to end up in thyroid storm.”

Dr. Tan adds that not having access to good healthcare, being uninsured or underinsured, or being too busy with other things going on in life to take care of oneself can all be contributing factors that lead people to not properly treat their hyperthyroidism. “Thyroid storm tends to happen in patients who have not had a lot of recent medical care, more commonly in people who are uninsured,” she adds.

Other triggers

There is also often some kind of precipitating event that can cause someone with uncontrolled thyroid hormone levels to develop thyroid storm, Dr. Cappola says. An infection, surgery or trauma, heart attack, or even childbirth, can cause you to go from regular hyperthyroidism to thyroid storm, she says. It’s not really known why these events can cause problems, Dr. Cappola adds, but it’s possible that for someone with poorly treated hyperthyroidism, the extra stress these things put on the body basically throws them over the edge.

In rare cases, thyroid storm can be caused by radioactive iodine therapy, a treatment that may be used for hyperthyroidism caused by Graves’ disease.

Symptoms of thyroid storm

According to the U.S. National Library of Medicine, these are the signs and symptoms of thyroid storm you should watch out for if you have hyperthyroidism:

  • Agitation

  • Change in alertness (consciousness)

  • Confusion

  • Diarrhea

  • Increased temperature

  • Pounding heart (tachycardia)

  • Restlessness

  • Shaking

  • Sweating

Most of these symptoms of thyroid storm are also symptoms of hyperthyroidism and many other non-thyroid conditions, says Dr. Tan. So, while you could be experiencing something that’s not an emergency (stay calm—that’s more likely), if you have hyperthyroidism and experience these symptoms or have a sharp uptick in severity of symptoms, you should always see your doctor to make sure everything is OK. “Even if it’s just your primary care doctor or urgent care, they can do labs for you to try and pin down what’s happening,” says Dr. Tan.

You should also keep an eye out for signs that the heart may be affected, which can happen as a result of a thyroid storm, Dr. Tan says. These include difficulty breathing, fluid retention, fever, and altered mental status. In the body, an excess of the thyroid hormone can lead to heart palpitations forcing the heart to pump faster, and thus, overworking it. Left untreated, this can lead to congestive heart failure when the heart can no longer pump the amount of blood the body needs. A buildup of fluid in the lungs or limbs can also occur with heart failure.

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Treatments for thyroid storm

“Treatments are fairly easy to administer so it’s easier to err on the side of being more aggressive,” says Dr. Cappola. The goal for thyroid storm treatment is twofold: Stop the production of additional thyroid hormone, and manage the hormones that are already circulating in the blood. While medications to stop new hormone production work pretty quickly, hormones already in the blood can take some time to metabolize, she explains. If a patient is experiencing heart symptoms, doctors will also administer a beta-blocker to get those under control while they wait for the thyroid hormones in the blood to metabolize. “Generally, we can get it under control in a few days,” says Dr. Cappola.

Long-term treatment and prevention

The most common cause of hyperthyroidism is Graves’ disease, which is an autoimmune condition and can’t be cured, says Dr. Cappola. So the most important thing for patients is to have a long-term treatment plan. Hyperthyroidism is typically treated with antithyroid drugs and/or beta-blockers (to control thyroid hormone’s impacts on the heart), radioactive iodine, or surgery to remove part or all of the thyroid. Iodine treatments and surgery can cause hypothyroidism, so your doctor will discuss the pros and cons of each treatment option and work with you to figure out which is the best to keep your thyroid levels in a safe place so that you aren’t plagued by symptoms or at risk for something more dangerous like thyroid storm.

Medically reviewed by Tia Jackson-Bey, MD, on February 03, 2020

Amy Marturana Winderl
Amy is a freelance journalist and certified personal trainer. She covers health and fitness, outdoors, travel, and finance. Her work has appeared on SELF, Bicycling, Earnest, and other publications. When she's not busy writing or editing, you can find her hiking, cooking, running, or lounging on the couch watching the latest true crime show on Netflix.