Graves' disease is an autoimmune disease that typically causes hyperthyroidism, in which the thyroid gland produces too much thyroid hormone and becomes overactive.
In 1 percent to 2 percent of cases, the thyroid produces an extreme amount of the key hormones involved in thyroid function-triiodothyronine (T3) and thyroxine (T4).
This can cause your heart rate, blood pressure, and body temperature to become uncontrollably high—what's known as a thyroid storm. This is dangerous and potentially life-threatening.
Causes and Risk Factors
The primary risk factor for thyroid storm is having untreated Graves' disease and/or hyperthyroidism. Additionally, women are at greater risk than men, and seniors are more at risk than younger people with Graves'/hyperthyroidism.
Even when the Graves' disease is identified and being treated, there are a number of other factors that raise your risk of thyroid storm:
Infection, specifically lung infections, throat infections, or pneumonia
Blood sugar changes, including diabetic ketoacidosis and insulin-induced hypoglycemia
Recent surgery on your thyroid gland or trauma to your thyroid
Abrupt withdrawal of your antithyroid medications
Radioactive iodine (RAI) treatment of your thyroid
Excessive palpation (handling/manipulation) of your thyroid gland
Exposure to a large quantity of iodine (such as an iodine-based contrast agent or the heart drug amiodarone)
Severe emotional stress
An overdose of thyroid hormone drugs
Toxemia of pregnancy and labor
Symptoms
Symptoms of thyroid storm are usually quite extreme and include:
A very high fever of 100 to 106 degrees
A very high heart rate, which can be as high as 200 beats per minute (BPM)
Palpitations, chest pain, and shortness of breath
High blood pressure
Confusion, delirium, and even psychosis
Extreme physical and muscle weakness
Extreme fatigue and exhaustion
Extreme restlessness, nervousness, and mood swings
Exaggerated reflexes, especially in knee and ankle areas
Difficulty breathing
Nausea, vomiting, and diarrhea
Profuse sweating or dehydration
Stupor or coma
Recent dramatic weight loss
Complications of thyroid storm include stroke and heart attack, which can lead to death.
Go to the ER
Whenever thyroid storm is suspected, you must go to the emergency room immediately. Thyroid storm requires immediate treatment, as it is life-threatening and can develop and worsen quickly.
Diagnosis
Physicians have developed a scoring system that helps them quickly assess symptoms and make a presumptive diagnosis of thyroid storm, so they can rapidly begin treatment.
The system involves measuring temperature, heart rate, gastrointestinal symptoms, neurological symptoms, and noting whether the patient has had a previous thyroid storm.
Sometimes, blood tests are done to look for high levels of thyroid hormones; a TSH (thyroid stimulating hormone) test may also be done. Because thyroid storm is a medical emergency, however, there is rarely time to wait for test results and treatment is started immediately.
Treatment
When treating thyroid storm, doctors often use the "five Bs":
Block the synthesis of thyroid hormone using antithyroid drugs: This is typically done right away with larger initial loading doses and frequent administration of additional doses. In patients who can't tolerate antithyroid drugs, lithium is sometimes used.
Block the release of thyroid hormone using a potassium iodide preparation: This is usually given after the antithyroid drugs and helps suppress thyroid hormone release.
Block T4 to T3 conversion using a corticosteroid drug, such as hydrocortisone
Use of a beta-blocker drug, such as propranolol, to reduce blood pressure and heart rate
Reduce the reabsorption of thyroid hormones with a bile acid sequestrate such as cholestyramine
Supportive treatment may also include cooling to help reduce body temperature, fluids to combat dehydration, and treatment of any other infections.
Typically, if the treatments are going to work, the improvement will be seen within 24 to 72 hours.
The mortality rate in people whose thyroid storm goes untreated is as high as 75 percent. When treated, mortality goes down to 20 percent to 30 percent.
When thyroid storm does not respond to these approaches, plasmapheresis, a blood filtering treatment, is sometimes done to remove thyroid hormone from the bloodstream. Only a small percentage of the hormone can be removed during each session, so it needs to be performed several times.
In rare cases, the thyroid is surgically removed, but physicians have to be particularly careful, as the surgery can precipitate a worsening of thyroid storm if hormone levels are already high.
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