Hyperthyroidism Latest Facts: Causes, Diagnosis, Symptoms, Risk Factors, Prevention and Treatment

Hyperthyroidism refers to the abnormally high production of thyroid hormone by the thyroid gland, the butterfly-shaped organ located at the base of the neck below Adam’s apple. It is not swelling of the thyroid gland as is sometimes thought.

Enlarged Thyroid

Enlarged Thyroid

The disease usually occurs in adults between the ages of 20 and 40. However, it can occur at any age and is also seen in children and the elderly. It is less common than hypothyroidism.

The thyroid gland has a great impact on the body: its main task is to regulate the metabolism of the body’s cells. It, therefore, determines the speed of the “engine” of our cells and organs and the speed at which the “fuels” are used: lipids (fats), proteins, and carbohydrates (sugar). In people with hyperthyroidism, the engine runs faster. For example, they may feel nervous, have frequent bowel movements, tremble and lose weight.

At rest, the body uses energy to maintain its vital functions: blood circulation, brain function, breathing, digestion, maintaining body temperature, etc. This is called basal metabolism and is partly controlled by thyroid hormones. The amount of energy used varies from person to person, depending on height, weight, age, gender, and thyroid activity.

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Causes of Hyperthyroidism

Graves’ disease

This is by far the most common cause of hyperthyroidism (about 90% of cases). It is an autoimmune disease: antibodies overstimulate the thyroid to produce more hormones. Sometimes the disease also attacks other tissues, such as the eyes.

Thyroid nodules

Nodules are small masses that form in the thyroid gland, either individually or in groups. Not all nodules make hormones, but those that do (called “toxic” nodules) can lead to hyperthyroidism.


If the thyroid is inflamed, it can also cause an excess of thyroid hormones in the blood. Often the cause of the inflammation is unknown. It may be contagious or occur after pregnancy. Usually, thyroiditis causes short-term hyperthyroidism, with the thyroid gland returning to normal function after a few months without intervention. Medications can help relieve symptoms until the disease ends. Thyroiditis develops into permanent hypothyroidism in only about 1 in 10 cases.

Possible Complications

Hyperthyroidism leads to increased metabolism and therefore increased energy expenditure. In the long term, untreated hyperthyroidism increases the risk of developing osteoporosis by affecting the absorption of calcium by the bones. It also increases the risk of developing a type of heart rhythm disorder called atrial fibrillation.

Severe untreated hyperthyroidism can lead to a thyrotoxic crisis. In a thyrotoxic crisis, all signs of hyperthyroidism are present and expressed at their highest level, which can lead to serious complications such as heart failure or coma. The person in a thyrotoxic crisis can be confused and agitated. This situation requires immediate medical attention.

Diagnosis of Hyperthyroidism

Symptoms of hyperthyroidism can be subtle, especially in older people. Only a blood test showing both a decrease in TSH levels and an increase in thyroid hormone (T4 and T3) levels can confirm the diagnosis.

TSH, T3, and T4 thyroid hormones

The thyroid gland secretes two main hormones: T3 (triiodothyronine) and T4 (tetraiodothyronine or thyroxine). In both cases, the term “iodine” is used because iodine is necessary for their production. The amount of hormones produced depends on the other glands. The hypothalamus tells the pituitary gland to produce TSH (thyroid-stimulating hormone). TSH in turn stimulates the thyroid gland to produce hormones.

Under- or over-activity of the thyroid gland can be detected by measuring blood levels of TSH. In hypothyroidism, TSH levels are high because the pituitary gland responds to a lack of thyroid hormones (T4 and T3) by secreting more TSH. The pituitary gland thus tries to stimulate the thyroid gland to produce more hormones. In hyperthyroidism (when there is too much thyroid hormone), the opposite happens: TSH levels are low because the pituitary gland senses an excess of thyroid hormones in the blood and stops stimulating the thyroid gland. TSH levels are often abnormal even in the early stages of thyroid problems.

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Symptoms of Hyperthyroidism

If hyperthyroidism is mild, it may go unnoticed. Also, in older people, the symptoms are often less pronounced. The following are the main symptoms of hyperthyroidism:

  • Rapid heart rate (often more than 100 beats per minute at rest) and palpitations.
  • Excessive sweating and sometimes hot flushes.
  • Hand tremors.
  • Difficulty falling asleep.
  • Mood swings.
  • Nervousness (anxiety).
  • Frequent bowel movements.
  • Muscle weakness.
  • Shortness of breath.
  • Weight loss despite normal or even increased appetite.
  • Changes in the menstrual cycle.
  • The appearance of goiter at the base of the neck.
  • Abnormal protrusion of the pupils of the eyes (exophthalmos) and irritated or dry eyes in the case of Graves’ disease.
  • In rare cases redness and swelling of the skin on the legs in the case of Graves’ disease.

Persons at Risk of Hyperthyroidism and Risk Factors

People at risk

  • Women are at higher risk: there are 8 women for every man with hyperthyroidism.
  • The prevalence of Graves’ disease is higher in families with a previous diagnosis of thyroid disease.

Risk factors

Medical science does not know the specific risk factors for hyperthyroidism. In most cases, it is an autoimmune disorder (Graves’ disease), the exact cause of which is unknown.

Some experts believe that adding iodine to table salt could significantly increase the incidence of hyperthyroidism, but only in the small proportion of people already at risk1. The addition of iodine to table salt is intended to prevent iodine deficiency, which was the main cause of hypothyroidism at the beginning of the 20th century.

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Prevention of Hyperthyroidism

It is currently not possible to prevent hyperthyroidism.

Measures to prevent complications:

Adequate rest

Get a good night’s sleep. If necessary, get some sleep in the early afternoon.


  • Ensure adequate calcium intake as an overactive thyroid contributes to bone mineral loss.
  • Eat smaller meals and eat, more often.
  • Avoid caffeine, which can further stimulate the body: coffee, tea, energy drinks, cola-type soft drinks, and chocolate contain varying amounts of it.
  • Do not take supplements or multivitamins containing natural iodine.
  • Also avoid highly salted foods and seaweed as they contain high levels of iodine, which can interfere with the synthesis of thyroid hormones. Seafood is not contraindicated for people with hyperthyroidism, even if it contains some iodine.
  • If there has been weight loss, treatment of hyperthyroidism (without increasing food intake) is usually sufficient to regain the lost weight. However, in rare cases, a slightly higher calorie and protein diet may be necessary until treatment takes effect and thyroid function returns to normal. Consult your doctor or dietician before changing your eating habits.

Please note! Some foods make iodine unavailable to the thyroid: all cabbage-like plants (cauliflower, broccoli, turnip, beetroot, rutabaga, and mustard), soybeans, millet, peanuts, and pine nuts. These effects are due to the isothiocyanates they contain. This property may be of interest to people suffering from hyperthyroidism. However, the isothiocyanate content of these foods is too low to help treat hyperthyroidism. To achieve a therapeutic effect, one would have to eat a disproportionate amount. Moreover, isothiocyanates are inactivated during the cooking process.


  • In hyperthyroidism, vigorous cardio exercise (e.g. running, racquet sports, cardio exercise, and exercise on exercise machines) should be avoided as the body is already in an “overactive” state. Walking (moderate intensity) and swimming are usually well tolerated.
  • Regular exercise is particularly important after the problem has been treated, as it helps to prevent or limit bone demineralization, say experts at the Mayo Clinic.

Preventing and alleviating eye problems

Some tips to reduce eye irritation, which is common in people with autoimmune hyperthyroidism (Graves’ disease):

  • Don’t smoke, as smoking also increases the risk of exophthalmos.
  • Avoid direct wind
  • Avoid bright light by wearing sunglasses as the eyes are more sensitive to ultraviolet light.
  • Use lubricating eye drops (tear drops during the day and gels at bedtime).
  • Apply a cold compress to the eye to reduce irritation.
  • At night, elevate your head with a pillow to relieve pressure around the eye.
  • If symptoms are still unpleasant, consult a doctor.

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Treatment of Hyperthyroidism

The first priority is to restore euthyroidism, that is, normal thyroid function, as soon as possible to relieve the patient and avoid complications. Treatment with antithyroid drugs or radioactive iodine usually achieves this goal within a few months, depending on the severity of hyperthyroidism.

If this treatment fails, surgical removal of the thyroid gland is sometimes considered.

Each of these options has advantages and disadvantages, and people should consult their doctor to decide which is best for them.

Thyroid medications

These medications (propylthiouracil or methimazole) prevent the production of new thyroid hormones without causing permanent damage. They restore normal hormone levels after 2-4 months of treatment. It is often necessary to continue treatment for 1.5 years. Sometimes hyperthyroidism may reappear.

Treatment with radioactive iodine

Radioactive iodine (in low concentrations) permanently destroys part of the thyroid cells, so the thyroid gland produces fewer hormones. Radioactive iodine that is not absorbed by the thyroid is eliminated from the body in a few days. The treatment allows a return to normal after about 3 to 6 months. In more than 90% of cases, one dose of radioactive iodine is sufficient (if not, a second dose is sometimes offered).

This treatment often leads to a permanent state of hypothyroidism. Hypothyroidism is much easier to treat than hyperthyroidism. Synthetic thyroid hormones in tablet form taken daily for life can correct hypothyroidism (Eltroxin®, Levothyroid®, or Synthroid®) without causing side effects.

Pregnant and breastfeeding women should not take this treatment because radioactive iodine can affect the thyroid gland of the fetus or infant.

Pregnancy after treatment with radioactive iodine

Women who wish to become pregnant are advised to wait 6 to 12 months after radioactive iodine treatment before conceiving a child. This is because radioactive iodine can harm the development of the fetus.

Also, it is desirable for the expectant mother to have her thyroid hormone levels well controlled before becoming pregnant. The need for thyroid hormones generally increases in the first trimester of pregnancy (weeks 1-13). For pregnant women taking synthetic hormones, blood TSH levels should be monitored each trimester by a family physician or endocrinologist. After delivery, the dosage is often reduced.

A man being treated with radioactive iodine should wait 3 months before conceiving.

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Thyroid gland removal

Complete or partial removal of the thyroid gland by surgery (thyroidectomy) may be considered but is rarely used.

Specific Treatments for the different symptoms

Additional medications are sometimes used as needed to relieve specific symptoms. Beta-blockers (e.g., propranolol) are sometimes prescribed to relieve palpitations and reduce heart rate and tremor.

The eye problems that accompany Graves’ disease, if severe, may require treatment with corticosteroids (to relieve inflammation behind the eye) or surgery (to reduce pressure on the eye). Smokers may respond poorly to this treatment. In fact, it is strongly recommended that you do not smoke if your eye symptoms are a result of graves disease.

Final thoughts

Hyperthyroidism is a very uncomfortable condition because the symptoms have a significant impact on quality of life. In addition, it can have serious health consequences, especially for the heart and bones. For this reason, the patient is usually referred to an endocrinologist who is a thyroid specialist.

If you have it, treatment for hyperthyroidism is usually quite good. The key to success is to follow the doctor’s recommendations exactly. This means, for example, taking blood tests on time, even if they may be frequent, taking medication as prescribed, and coming to follow-up appointments. This way, you can get the most out of your medical care. It is also very important that you do not smoke.

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