Image of thyroid gland responsible for hyperthyroidism.
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January 24, 2022

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Hyperthyroidism is a condition in which the thyroid gland is overactive and produces too much thyroid hormone. If left untreated, hyperthyroidism can lead to other health problems. Some of the most serious involve the heart (rapid or irregular heartbeat, congestive heart failure) and the bones (osteoporosis). 

Endocrine Connection 

Graves’ disease is the most common cause of hyperthyroidism. It occurs when the immune system attacks the thyroid gland, causing it to enlarge and make too much thyroid hormone. It typically runs in families with a history of thyroid disease or other autoimmune conditions.

Pregnant women with uncontrolled Graves’ disease are at greater risk of miscarriage, premature birth, and having a baby with low birth weight. Graves’ disease also can cause swelling behind the eyes that sometimes makes them bulge outward. This condition is called Graves' ophthalmopathy or Thyroid Eye Disease and is relatively rare.

Less common causes of hyperthyroidism include: 

  • Thyroid nodules: Lumps on the thyroid gland that may secrete too much thyroid hormone 
  • Subacute thyroiditis: A painful inflammation of the thyroid typically caused by a virus 
  • Lymphocytic thyroiditis: A painless inflammation caused by lymphocytes (a type of white blood cell) inside the thyroid 
  • Postpartum thyroiditis: Thyroiditis that develops shortly after pregnancy 
  • Certain medications, such as amiodarone and some cancer immunotherapies 

Your doctor will perform a physical examination and order blood tests to measure your hormone levels; we collectively call these labs thyroid function tests (TFTs) – TSH, free T4, total T3. 

TSH test: TSH is a hormone released from your pituitary gland when there is not enough thyroid hormone in the system. TSH will be low if there is too much thyroid hormone (hyperthyroidism). 

Free T4 and total T3 test: T3 and T4 are thyroid hormones, and these will be high in hyperthyroidism. 

It is important to know that biotin can interfere with the testing of thyroid function in many labs, and you should check with your doctor to see if you should stop your biotin supplement beforehand. To determine the type of hyperthyroidism you have, your doctor may do different tests: 

Thyrotropin Receptor Antibody (TRAb) TestAn antibody test called thyrotropin receptor antibody test (TRAb) can detect the antibody in the blood which causes Graves’ Disease.  

Radioactive Iodine Uptake Test: The thyroid absorbs iodine from your blood and uses it to make thyroid hormone. When the thyroid produces too much thyroid hormone, it absorbs more iodine. This test measures how much iodine your thyroid collects from the bloodstream (certain conditions have low uptake and others have high uptake). This test involves swallowing a capsule containing a small, harmless amount of radioactive iodine. The amount of iodine taken up by your thyroid is then measured. A high uptake of radioactive iodine suggests Graves’ disease.

Thyroid Ultrasound: A thyroid gland impacted by Graves’ disease is often enlarged and may have increased blood flow; both of these elements can be visualized by thyroid ultrasound. Ultrasound can also be performed if there are any concerns for a thyroid hormone-producing nodule (called a toxic nodule), which is an alternate cause of hyperthyroidism. 

Some of Hyperthyroidism’s symptoms include: 

  • Feeling too hot 
  • Increased sweating 
  • Muscle weakness 
  • Trembling hands 
  • Rapid heartbeat 
  • Tiredness/fatigue 
  • Weight loss 
  • Diarrhea or frequent bowel movements 
  • Irritability and anxiety 
  • Eye problems, such as irritation or discomfort 
  • Menstrual irregularities 
  • Infertility 

Many of the signs and symptoms of hyperthyroidism may occur in other conditions. An endocrinologist, a specialist in hormone-related conditions, can help diagnose and treat hyperthyroidism. If you have ever been treated for hyperthyroidism, or are currently being treated, see your doctor regularly so that your condition can be monitored. It is important to ensure that your thyroid hormone levels are normal and that you're getting enough calcium to keep your bones strong. 

Treatment for hyperthyroidism will depend on its cause, your age and physical condition, and how serious your thyroid problem is. Sometimes, only observation is needed, but most of the time, some treatment is helpful.  Available treatments include: 

Antithyroid medications: These drugs lower the amount of hormone the thyroid gland makes. The preferred drug is methimazole. For pregnant or breastfeeding women, propylthiouracil (PTU) may be preferred. Because PTU has been linked to greater side effects, it is not used routinely outside of pregnancy. Both of these drugs control, but may not cure, hyperthyroidism. These medications have important side effects that should be discussed with your doctor. 

Surgery: Surgical removal of the thyroid gland (thyroidectomy) is a permanent solution, but not usually preferred, because of the risk of damage to the nearby parathyroid glands (which control calcium levels in the body) and to the nerves to the larynx (voice box). Doctors may recommend surgery when either antithyroid medication or radioactive iodine therapy would not be appropriate. 

Beta blockers: These drugs (such as atenolol) do not lower thyroid hormone levels, but can control many troubling symptoms, especially rapid heart rate, trembling, and anxiety.  

This treatment will cure the thyroid problem, but usually leads to permanent destruction of the thyroid. You will likely need to take thyroid hormone pills for the rest of your life to provide normal hormone levels. This treatment is generally tolerated very well but can worsen Graves eye disease if it is present. 

The thyroid gland uses iodine to make thyroid hormone. It absorbs the iodine from the foods we eat. Similarly, the thyroid gland absorbs the RAI when it swallowed. Then, the radiation attached to the iodine damages the thyroid cells. Over time, the thyroid gland produces less thyroid hormone. Because no other organ in the body use iodine, the RAI does not affect any other part of the body.  

RAI, also called iodine 131 (I-131), is given as a single-dose capsule or liquid. Most often, you will not need to stay in the hospital. It can take 6 weeks to 6 months to see the full effects of RAI treatment. During this time, your thyroid blood levels will be monitored regularly. You may also need to take antithyroid drugs. 

For safety reasons, these people should not get RAI treatment: 

  • Pregnant and breastfeeding women or those planning to become pregnant in the next six months 
  • People who cannot follow radiation safety precautions 
  • Young children who haven’t tried other treatment options first 
  • Some people with active Graves’ ophthalmopathy (thyroid eye disease) 

RAI is generally safe. Sometimes neck pain can develop right after the treatment. This does not last long, and pain medicine can help relieve the discomfort. Most people will develop hypothyroidism (underactive thyroid) after treatment. This drop in the amount of thyroid hormones in the body may be temporary, but it is often permanent. It is easily treated with synthetic (manmade) thyroid hormone, levothyroxine. The risk of thyroid cancer does not increase in patients who receive RAI as a treatment of hyperthyroidism. 

Preparing for Radioactive Iodine Treatment 

If you are taking antithyroid drugs, stop these medications five to seven days before treatment. Do not stop taking beta blockers (drugs such as atenolol) if your doctor has prescribed them. 

Avoid drugs and foods that contain high levels of iodine for as long as your doctor instructs. Foods high in iodine include iodized salt, seaweed and other seafood, and dairy products. Multivitamins often contain iodine, so check the labels. 

Some radiation stays in your body for a few days after RAI treatment. Your health care provider will give you a list of precautions to take after treatment to minimize others’ exposure to the radiation. The radiation is eliminated in your urine, stool, and saliva. So, good hygiene is most important.  

Follow these safety measures after RAI treatment: 

  • Sleep in a separate bed (more than six feet away) from other adults for three or more days after treatment. Sleep apart from children and pregnant women for two weeks or longer. 
  • In daytime, keep more than six feet away from children and pregnant women for at least one day. 
  • Avoid prolonged time in public places or transportation (planes, trains, buses) for at least three days. 
  • Do I have hyperthyroidism? 
  • What is the cause of my hyperthyroidism?  
  • What treatment do I need for hyperthyroidism?  
  • What are the risks and benefits of each of my treatment options? 
  • What are the pros and cons of RAI compared with other treatments? 
  • How often do I need monitoring for each type of treatment?  
  • What should I do about my hyperthyroidism if I want to get pregnant?  
  • What else can I do to stay healthy? 
  • Should I see an endocrinologist for my care? 

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