Which of the following symptoms would lead you to suspect hyperthyroidism in a patient you are evaluating?

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 be. You may even speak far more quickly than you usually do.

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:

• trauma
• surgery
• severe emotional distress
• stroke
• diabetic ketoacidosis
• congestive heart failure
• pulmonary embolism

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

• racing heart rate (tachycardia) that exceeds 140 beats per minute, and atrial fibrillation
• high fever
• persistent sweating
• shaking
• agitation
• restlessness
• confusion
• diarrhea
• unconsciousness

Individuals with hyperthyroidism who experience any symptoms of thyroid storm are typically admitted to an 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 milli–international units per liter (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.

People experiencing thyroid storm 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.

Thyroid storm requires immediate, aggressive emergency medical attention. When left untreated, thyroid storm can cause congestive heart failure or fluid-filled lungs.

The mortality rate for people with untreated thyroid storm is estimated to be 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).

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

How is hyperthyroidism diagnosed?

Diagnosing hyperthyroidism starts with a complete medical history, followed by a physical exam. To confirm a diagnosis, your child’s doctor may:

• request blood tests to check the levels of your child’s thyroid hormones and/or thyroid-stimulating antibodies (a test for Graves disease)
• perform thyroid imaging studies, such as a thyroid scan or ultrasound, to determine the size, shape, function, and position of the thyroid gland

How is hyperthyroidism treated?

Graves disease

Graves disease is the most common cause of hyperthyroidism in children and adolescents. The goal of treatment is to decrease the function of the thyroid gland back to normal so that it produces a normal amount of thyroid hormone.

There are three types of treatment for Graves disease:

• Antithyroid drugs work by blocking the thyroid gland’s ability to make thyroid hormone. These drugs do not damage the thyroid gland itself. In many patients, antithyroid drugs can maintain normal thyroid hormone levels for many years. Some patients who respond well to antithyroid drugs may eventually be able to stop taking them and remain with normal thyroid function. Antithyroid drugs are generally safe but can have rare, serious side effects, so they need careful monitoring.
• Radioactive iodine uses the thyroid gland’s natural need for iodine to treat overactive thyroid cells. Radioactive iodine is absorbed by and permanently destroys the thyroid gland, but does not affect other parts of the body. Once the thyroid gland is destroyed, the patient will need to take thyroid hormone medication.
• Surgery to remove the thyroid gland is very effective for treating Graves disease. This procedure is generally safe but rarely can have serious complications. For this reason, it is important that the procedure be performed by an experienced thyroid surgeon. Lifelong thyroid hormone medication is needed after the thyroid is removed.

Additional treatments for Graves disease may include medications to improve symptoms (like palpitations and anxiety), which can be used temporarily until thyroid hormone levels are brought down to normal by one of the three treatments above.

Neonatal Graves disease

Neonatal Graves disease is a temporary condition that lasts only until the mother’s thyroid-stimulating antibodies have been cleared from the baby’s circulation. Until the condition goes away, antithyroid drugs are used to control the baby’s overactive thyroid. With prompt treatment, babies usually recover completely within a few weeks. However, either hyperthyroidism or hypothyroidism (low thyroid function) may occur later in the first year of life, so continued monitoring by a physician is important.

Autonomous thyroid nodules

Autonomous thyroid nodules are usually benign. Their treatment depends on how much thyroid hormone they produce, and on whether this is causing symptoms of thyroid hormone excess.

• Autonomous nodules that are slightly overactive and cause no symptoms. It can often be observed without treatment.
• Nodules that are very overactive or that cause symptoms can be treated with medication, surgery, or (in patients over 18 years) radioactive iodine ablation.

Our approach to treating autonomous nodules is slightly different than that recommended by the American Thyroid Association, which recommends surgery for all autonomous nodules in children. Our approach is based on our extensive experience with this condition — which was published after the release of the American Thyroid Association guidelines — showing that with careful evaluation, some autonomous nodules can be managed safely without surgery.

Thyroiditis

Hyperthyroidism caused by thyroiditis is usually temporary and goes away within eight to 12 weeks. Because we cannot make this hyperthyroidism go away any faster, treatment focuses on medications to control any symptoms (like palpitations and anxiety) until the condition goes away on its own. Sometimes, this type of hyperthyroidism is followed by a period of hypothyroidism (low thyroid function), so continued monitoring by a physician is important.

How we care for hyperthyroidism at Boston Children’s Hospital

Our Thyroid Center is one of the first and largest centers in the United States devoted exclusively to the care of children with thyroid disease. Our clinicians and staff are involved in numerous studies about the various aspects of thyroid disease and thyroid function in childhood.

Our center is distinguished by our extensive experience in:

• nuclear medicine imaging of the thyroid (thyroid scan) to determine the cause of hyperthyroidism
• radioactive iodine therapy for hyperthyroidism — this therapy, given as a capsule or liquid, uses the thyroid gland’s natural need for iodine to treat overactive thyroid cells
• surgery for hyperthyroidism (including Graves disease and autonomous thyroid nodules), when appropriate