Hyperthyroidism: Symptoms, Causes and Treatment

Hyperthyroidism is caused by an excess production of thyroid hormones and can lead to weight loss, high blood pressure and poor heat tolerance. Here's everything you need to know about the condition.
Hyperthyroidism: Symptoms, Causes and Treatment

Written by Daniela Andarcia

Last update: 29 March, 2023

Hyperthyroidism is one of the best-known diseases of the thyroid gland. It’s shaped like a butterfly and is located on the neck. It’s responsible for producing the hormones tetraiodothyronine (T4) and triiodothyronine (T3), which are involved in the regulation of metabolism.

When there’s an excess in the production of thyroid hormones (more than what the body needs) we’re talking about hyperthyroidism. Discover more about the symptoms, causes, and treatment of this disease.

What are the symptoms of hyperthyroidism?

An excess in the hormones T4 and T3 is the cause of a metabolic rate that’s too high, which, in turn, produces the so-called hypermetabolic state. During it, you may experience symptoms such as increased blood pressure and heart rate, tremors in the hands, excessive sweating, low heat tolerance, frequent bowel movements, weight loss, and irregular menstrual cycles.

Also, the thyroid gland may show signs of swelling and progress to a goiter. Changes that present a more prominent appearance, associated with Graves’ disease, also occur in the eyes.

Other symptoms of hyperthyroidism that are not uncommon include the following:

There are a number of symptoms that require immediate medical attention. These are dizziness and shortness of breath, as well as (obviously) loss of consciousness and fast or irregular heartbeat. According to a study published in the Indian Heart Journal, this disease is also among the causes of atrial fibrillation (AF), a type of arrhythmia capable of causing strokes and congestive heart failure.

Medical consultation for hyperthyroidism.
Hyperthyroidism is urgent in some life-threatening situations, such as arrhythmias.

What causes hyperthyroidism?

Hyperthyroidism is caused by various reasons and disorders, most notably the following:

  • Graves’ disease – According to a study published in Therapeutic Advances in Endocrinology and Metabolism, this autoimmune condition is one of the most common causes of hyperthyroidism. It’s capable of making antibodies that stimulate the thyroid gland by increasing the secretion of its hormones. Similarly, it tends to run in families.
  • Excess iodine: According to a study published in Endocrinology and Metabolism, iodine is a key compound of thyroid hormones, so consuming too much can increase its production.
  • Thyroiditis or inflammation of the thyroid: There’s scientific evidence that thyroiditis can lead to hyperthyroidism.
  • Thyroid nodules: These are benign tumors in the thyroid gland that, according to studies, can be overactive and increase the production of hormones. Also, they tend to skin more frequently in older adults.
  • Excessive intake of thyroid medication: This often occurs when hypothyroid patients take excessive amounts of their medicine.
  • Tumors: Tumors of the ovaries or testicles, as well as those of the pituitary gland, can cause the condition.

Who is more likely to develop hyperthyroidism?

This disease can be subject to factors such as age, sex, and eating habits. Women, those over 60 years of age, pregnant women, those with a family history, and those with excessive amounts of iodine are particularly at risk.

Also at risk of hyperthyroidism are those who have had previous thyroid problems, such as goiter, or patients with pernicious anemia, type 1 diabetes, and primary adrenal insufficiency (Addison’s disease).

How is an overactive thyroid diagnosed?

The first part of the diagnosis is to review the medical history and do a physical examination. These can reveal the more familiar symptoms, such as weight loss, racing heartbeat, and high blood pressure.

Then some tests are recommended to confirm and learn more about the nature of the disease. Among them, the measurements of TSH, T4, T3, and free T4 stand out. As a complement, cholesterol and triglycerides are analyzed.

Regarding the images of the gland, the most requested are the following:

  • Scintigraphy and iodine uptake of the thyroid
  • Ultrasound or sonography
  • CT scan or MRI

What are the treatments for hyperthyroidism?

At present, there are several drugs and therapies recommended to treat this disease. We’ll tell you what they are.


There are two types of drugs recommended for this disease: antithyroids and beta-blockers. Firstly, antithyroid drugs reduce hormone production and are usually taken for one to two years. Methimazole, for example, is one of the most prescribed.

In second place are beta blockers. They are prescribed to reduce symptoms of this disease (tremors, rapid heart rate, and nervousness). In addition, they have an immediate effect, so they can be alternated with other more lasting treatments. An example is propranolol.

Radioactive iodine therapies

According to research published in the Saudi Medical Journal, radioactive iodine therapy has established itself as an effective treatment for hyperthyroidism. These consist of taking it liquid or in capsule form, as the substance is capable of destroying the cells of the thyroid gland that produce hormones.

Although it doesn’t affect other tissues in the body, this treatment can lead to hypothyroidism. However, that would be much easier to treat than an overactive thyroid. Likewise, other side effects are evident, such as dry mouth and eyes and changes in taste.

Radioactive iodine for the thyroid.
Radioactive iodine treatment is gaining more and more ground due to improvements in its safety.


Surgery to remove a section, or all, of the thyroid gland are rare. They’re usually performed on patients with excessively large goiters or pregnant women who are unable to receive antithyroid drug medication.

If a part is removed, supplements must be taken to avoid hypothyroidism (caused by a thyroid gland now making too few hormones). If it’s completely removed, the medication must be for life.

A disease that affects your whole life

Diet plays a fundamental role in the treatment and prevention of this disease. You should consult your doctor to create a healthy eating plan, take supplements, and exercise.

However, since hyperthyroidism is characterized by reduced and weakened bone mass, special care should be taken with the intake of calcium and vitamin D during treatment. Hyperthyroidism is a disease linked to the regulation of metabolism, and that is key to understanding its signs.

Fortunately, there are scientifically-proven effective treatments, such as antithyroid medications and beta-blockers, radioactive iodine therapies, and, ultimately, surgery. Each case will depend on its evolution to be addressed.

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