1 What is Hyperthyroidism?

Hyperthyroidism is a condition in which the thyroid gland is overactive and makes excessive amounts of thyroid hormone.

The thyroid gland is an organ located in the front of your neck and releases hormones that control your

  • metabolism,
  • breathing,
  • heart rate,
  • nervous system,
  • weight,
  • body temperature,
  • and many other functions in the body.

When the thyroid gland is overactive (hyperthyroidism) the body’s processes speed up and you may experience

among other symptoms. 

2 Symptoms

There are several signs and symptoms of hyperthyroidism, which include:


  • Increased sweating
  • Sensation of warmth
  • Oversensitivity to heat
  • Warm, moist palms
  • Palpitations
  • Increased appetite
  • Diarrhoea
  • Weight loss
  • Dry, thin skin that flushes easily
  • Hair loss
  • Goitre
  • Shakiness/trembling
  • Shortness of breath
  • Overactivity
  • Tiredness/exhaustion
  • Increased sex drive
  • Enlargement of breasts in men
  • Pretibial myxoedema

Eye Complaints

  • Staring eyes
  • Conjunctivitis
  • Corneal ulceration
  • Dry/gritty eyes
  • Painful eyes
  • Double vision


  • Weak, less defined muscles (wasting)
  • Loss of muscle strength
  • Aches and pains

Menstrual Disorders

  • No periods
  • Longer or shorter cycle
  • Infertility 

Mental and Emotional

  • Mood changes
  • Nervousness, anxiety, excitability
  • Insomnia/racing thoughts
  • Talkativeness

3 Causes

Common causes of hyperthyroidism in adults include:

Diffuse Toxic Goiter (Graves' Disease)

Overactivity of the entire thyroid gland caused by antibodies in the blood which stimulate the thyroid to grow and secrete excessive amounts of thyroid hormone.

Toxic Adenoma ("hot nodule")

A dominant thyroid nodule, or lump, is overactive and secretes excess thyroid hormone.

Toxic Multinodular Goiter(Plummer's disease)

One or more nodules or lumps in the thyroid becomes overactive.

Subacute Thyroiditis

  • Hyperthyroid phase of subacute thyroiditis, caused by viral infection or postpartum inflammatory process.
  • Due to thyroid inflammation, excess hormone is released into the blood circulation.
  • More than 90% of affected individuals will go back to normal thyroid function without treatment.
  • Drug-Induced Hyperthyroidism
      • Iodine-induced hyperthyroidism: older population, typically in setting of preexisting nontoxic nodular goiter
      • amiodarone
      • Iodine-containing contrast material used in radiology studies

4 Making a Diagnosis

The health care provider will do a physical exam to make a diagnosis of hyperthyroidism. The exam may find the following:

  • High systolic blood pressure
  • Increased heart rate
  • Enlarged thyroid gland
  • Shaking of the hands
  • Swelling or inflammation around the eyes
  • Very strong reflexes
  • Skin, hair and nail changes

Blood tests are also ordered to measure your thyroid hormones TSH, T3, and T4.

You may also have blood tests to check:

  • Cholesterol levels
  • Glucose

Imaging tests of the thyroid may also be needed, including:

  • Radioactive iodine uptake and scan
  • Thyroid ultrasound

5 Treatment

No single treatment is best for all patients with hyperthyroidism. The appropriate choice of treatment will be influenced by your age, the type of hyperthyroidism that you have, the severity of your hyperthyroidism, other medical conditions that may be affecting your health, and your own preference.


Drugs known as antithyroid agents—methimazole or in rare instances propylthiouracil may be prescribed if your doctor chooses to treat the hyperthyroidism by blocking the thyroid gland’s ability to make new thyroid hormone.

Methimazole is presently the preferred one due to less severe side-effects. These drugs work well to control the overactive thyroid, bring quick control of hyperthyroidism and do not cause permanent damage to the thyroid gland. For patients with toxic nodular or multinodular goiter, antithyroid drugs are sometimes used in preparation for either radioiodine treatment or surgery.

Antithyroid drugs cause allergic reactions. Common minor reactions are red skin rashes, hives, and occasionally fever and joint pains. A rarer (occurring in 1 of 500 patients), but more serious side effect is a decrease in the number of white blood cells. Such a decrease can lower your resistance to infection. Very rarely, these white blood cells disappear completely, producing a condition known asagranulocytosis, a potentially fatal problem if a serious infection occurs.

If you are taking one of these drugs and get an infection such as a fever or sore throat, you should stop the drug immediately and have a white blood cell count that day. Even if the drug has lowered your white blood cell count, the count will return to normal if the drug is stopped immediately.

But if you continue to take one of these drugs in spite of a low white blood cell count, there is a risk of a more serious, even life-threatening infection. Liver damage is another very rare side effect. A very serious liver problem can occur with PTU use which is why this medication should not generally be prescribed.

You should stop either methimazole or PTU and call your doctor if you develop yellow eyes, dark urine, severe fatigue, or abdominal pain.


Another way to treat hyperthyroidism is to damage or destroy the thyroid cells that make thyroid hormone. Because these cells need iodine to make thyroid hormone, they will take up any form of iodine in your blood stream, whether it is radioactive or not.

The radioactive iodine used in this treatment is administered by mouth, usually in a small capsule that is taken just once. Once swallowed, the radioactive iodine gets into your blood stream and quickly is taken up by the overactive thyroid cells. The radioactive iodine that is not taken up by the thyroid cells disappears from the body within days. Over a period of several weeks to several months (during which time drug treatment may be used to control hyperthyroid symptoms), radioactive iodine destroys the cells that have taken it up.

The result is that the thyroid or thyroid nodules shrink in size, and the level of thyroid hormone in the blood returns to normal. Sometimes patients will remain hyperthyroid, but usually to a lesser degree than before. For them, a second radioiodine treatment can be given if needed. More often, hypothyroidism (an underactive thyroid) occurs after a few months and lasts lifelong, requiring treatment.

In fact, when patients have Graves’ disease, a dose of radioactive iodine is chosen with the goal of making the patient hypothyroid so that the hyperthyroidism does not return in the future. Hypothyroidism can easily be treated with a thyroid hormone supplement taken once a day.

Radioactive iodine has been used to treat patients for hyperthyroidism for over 60 years and has been shown to be generally safe. Importantly, there has been no clear increase in cancer in hyperthyroid patients that have been treated with radioactive iodine.


Your hyperthyroidism can be permanently cured by surgical removal of most of your thyroid gland. This procedure is best performed by a surgeon who has much experience in thyroid surgery.

An operation could be risky unless your hyperthyroidism is first controlled by an antithyroid drug or a beta-blocking drug. Usually for some days before surgery, your surgeon may want you to take drops of nonradioactive iodine—either Lugol’s iodine or supersaturated potassium iodide (SSKI).

This extra iodine reduces the blood supply to the thyroid gland and thus makes the surgery easier and safer. Although any surgery is risky, major complications of thyroid surgery occur in less than 1% of patients operated on by an experienced thyroid surgeon.

These complications include damage to the parathyroid glands that surround the thyroid and control your body’s calcium levels (causing problems with low calcium levels) and damage to the nerves that control your vocal cords (causing you to have a hoarse voice).

After your thyroid gland is removed, the source of your hyperthyroidism is gone and you will likely become hypothyroid. As with hypothyroidism that develops after radioiodine treatment, your thyroid hormone levels can be restored to normal by treatment once a day with a thyroid hormone supplement.


No matter which of these three methods of treatment are used for your hyperthyroidism, your physician may prescribe a class of drugs known as the beta adrenergic blocking agents that block the action of thyroid hormone on your body. They usually make you feel better within hours to days, even though they do not change the high levels of thyroid hormone in your blood.

These drugs may be extremely helpful in slowing down your heart rate and reducing the symptoms of palpitations, shakes, and nervousness until one of the other forms of treatment has a chance to take effect. Propranolol was the first of these drugs to be developed.

Some physicians now prefer related, but longer-acting beta-blocking drugs such as atenolol, metoprolol, nadolol because of their more convenient once- or twice-a-day dosage.

6 Prevention

Treatment can control and cure the symptoms, but currently, there are no known ways to prevent hyperthyroidism.

Hyperthyroidism is a common condition, which affects the thyroid gland. In this, the thyroid gland makes an excess of the thyroid hormone. This condition is also known as an "overactive thyroid".

Some measures that may probably help to prevent thyroid disease include:

  • Quit smoking: Research suggests that people, who smoke, are more likely to develop Graves' disease and Graves' ophthalmopathy than non-smokers. Cigarette smoke has several toxins, mainly thiocyanates, which are especially harmful for the thyroid gland. These toxins can trigger thyroid disease in susceptible people. Therefore, in addition to all the other health problems that are caused by smoking, it can increase the risk and worsen existing thyroid disease.
  • Avoid excess soy: Soy is a good food, but excess intake of soy has been linked to increased risk of thyroid disease. Excess of unnatural forms of soy (such as soy powders, pills, smoothies, soy patties and potions) may injure your immune system and trigger thyroid problems. Intakes of natural forms of soy such as tofu, tempeh, miso soup etc in moderation is good and acceptable, but remember to stay away from excess soy as it may actually ruin your health.

Some measures that help to improve symptoms of hyperthyroidism:

  • Take your medications: If you are given antithyroid drugs (such as propylthiouracil and methimazole), they have to be taken for at least a year and often longer. These medications gradually reduce the symptoms by preventing the thyroid gland from producing excess amount of hormones. Symptoms improve in most patients in six to 12 weeks. It may cure the problem permanently in some, but many people may experience a relapse of symptoms in a few months to years. Taking antithyroid drugs at the recommended dose and duration is needed for effective control of symptoms. Taking beta blockers as recommended is also essential. These drugs do not reduce the level of thyroid hormone, but are useful to treat rapid heart rate and prevent palpitations caused because of excess thyroid hormones. Hence, they may be given until your thyroid hormone levels are closer to normal. Be sure to follow your doctor’s recommendations for all your medications.
  • Follow-up regularly: Regular follow-ups are recommended for people on treatment for hyperthyroidism. Your doctor may examine you and assess the effectiveness of treatment and modify it if needed.
  • Try relaxation: In hyperthyroid patients, a relaxed lifestyle and abstinence from high iodine intake may help to control the symptoms.

7 Lifestyle and Coping

Lifestyle modifications are necessary in order to cope with hyperthyroidism.

Be sure to see your doctor regularly so he or she can be sure that your hyperthyroidism treatment is working, that you are taking the right amount of medicine, and that you are not having any side effects.

If you are taking antithyroid medicine, take it at the same time every day.

If you have Graves' ophthalmopathy, you may need to use eyedrops to help moisten your eyes and wear sunglasses to protect your eyes.

To help reduce the symptoms of hyperthyroidism, you can:

  • Lower stress. This helps relieve symptoms of anxiety and nervousness.
  • Avoid caffeine. Caffeine can make symptoms worse, such as fast heartbeat, nervousness, and difficulty concentrating.
  • Quit smoking. If you have Graves' disease and you are a smoker, you are more likely to develop Graves' ophthalmopathy.

8 Risks and Complications

There are several risks and complications associated with hyperthyroidism.

If it is not treated, hyperthyroidism can lead to other health problems. They include:

  • Heart problems. A rapid heart rate, a heart rhythm disorder (called atrial fibrillation) or congestive heart failure can result.
  • Brittle bones (osteoporosis). Too much thyroid hormone can interfere with your body’s ability to incorporate calcium into your bones. Be sure to get enough calcium in your diet to prevent osteoporosis.
  • Eye problems due to Graves’ opthalmopathy. To relieve the symptoms of Graves' opthalmopathy:
      • Apply cool compresses to your eyes
      • Wear sunglasses
      • Use lubricating eyedrops
      • Elevate the head of your bed to reduce blood flow to your head
  • Red, swollen skin on the shins and feet due to Graves' disease. Try using over-the-counter creams containing hydrocortisone for relief.
  • Thyrotoxic crisis. A sudden worsening of hyperthyroidism symptoms that leads to a fever, rapid pulse and even delirium (symptoms of which can include decreased awareness and mental clarity, restlessness and agitation). See a doctor right away if this occurs.

9 Related Clinical Trials