An Overview of Thyroid Storm

A thyroid storm is a rare but dangerous and potentially life-threatening condition where the thyroid gland produces extremely high levels of thyroid hormone. It's most often due to an existing hyperthyroidism (overactive thyroid) disorder like the autoimmune condition called Graves' disease. Other factors, like infection, also may contribute to the risk.

Symptoms of a thyroid storm include uncontrolled hypertension (high blood pressure), a racing heart rate, and a high body temperature. Irregular heart rhythms and digestive system changes, like diarrhea or jaundice, also may be present.

This article explains thyroid storm symptoms, causes, and risk factors. It discusses how a thyroid storm is diagnosed and why aggressive treatment is necessary to try to prevent the worst outcomes.

Symptoms of Thyroid Storm

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
• 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.

Causes and Risk Factors

The primary risk factor for thyroid storm is an underlying hyperthyroidism, such as with untreated Graves' disease. There's also evidence to suggest that a thyroid storm can occur with an Epstein-Barr virus infection and in people diagnosed with COVID-19.

Even when the underlying 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
• 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

In rare cases, even an aspirin overdose can lead to a thyroid storm.

Diagnosing a Thyroid Storm

Healthcare providers 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
• 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.

Thyroid Storm Treatment

When treating thyroid storm, healthcare providers typically use multiple interventions meant to interfere with the excessive thyroid hormone levels causing it. Treatment includes:

• Blocking 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.
• Blocking the release of thyroid hormone using a potassium iodide preparation. This is usually given after the antithyroid drugs.  
• Blocking 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

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 48 hours. 

When thyroid storm does not respond to these approaches, plasmapheresis, a blood filtering treatment, is sometimes done to remove thyroid hormone from the bloodstream. In rare cases, the thyroid is surgically removed.

Summary

While a thyroid storm is rare, it is life-threatening. The symptoms of rapid heart rate, very high blood pressure, and extremely high body temperature are usually related to an underlying hyperthyroidism such as Graves' disease.

A thyroid storm needs to be diagnosed and treated immediately, typically with medications used to block thyroid hormone activity and lower the body's vital signs. If left untreated, 80% or more of thyroid storm cases prove fatal.

The potential for an underlying thyroid disorder is one good reason to keep up-to-date on your routine healthcare exams. Your healthcare provider can feel your thyroid to check if it's enlarged (a sign of hyperthyroidism) and order annual blood tests. They can ensure any treatment plan you need is designed to manage thyroid disease.