What Is Hyperthyroidism And How Many People Have It?

Hyperthyroidism is more common than people realize, but most don’t know much about the condition or how it affects people.

The thyroid is a butterfly-shaped gland that sits at the front of the neck and is responsible for producing hormones. The two major metabolic modulating hormones that the thyroid produces are called triiodothyronine (T3) and thyroxine (T4).

Hyperthyroidism occurs when a person's thyroid gland produces too many thyroid hormones. This condition can also occur when an individual consumes an excess of iodine, which the body uses to make T3 and T4 and is found in foods like fish, dairy, and iodized table salt.

When a person has hyperthyroidism, it can accelerate the body's metabolism, which leads to unintentional weight loss and a rapid and irregular heartbeat, along with other symptoms.

How common is hyperthyroidism?

It is estimated that about 1.3% of the US population¹ suffers from hyperthyroidism.

Hyperthyroidism is also more common in women.² Two in one hundred women are likely to develop hyperthyroidism, and two in one thousand men are likely to develop this condition.

Different causes of hyperthyroidism

There are a few different factors that can cause hyperthyroidism.

Some viral or genetic diseases can cause this condition, often resulting in additional symptoms to those that are regarded as typical hyperthyroidism symptoms. 

Here are three common causes of hyperthyroidism.

Graves' Disease

Graves' disease, named after Robert Graves, is the most common cause of hyperthyroidism and is diagnosed at a rate of about 20-30 cases per 100,000 per year.³ About 4 out of 5 cases of hyperthyroidism⁴ in the United States are caused by Graves' disease.

According to research, Graves' disease is caused by an autoimmune process in which antibodies stimulate the thyroid to overproduce thyroid hormones. Graves' disease is considered an autoimmune disease and is most common in young to middle-aged women, peaking at 30-50 years.

Subacute Granulomatous Thyroiditis (De Quervain Thyroiditis)

Subacute Granulomatous thyroiditis affects 4.9 people in 100,000⁵ annually in the US. It also occurs more often in women than men.

This condition causes initial hyperthyroidism and is usually followed by a typical period of transient hypothyroidism, also known as an underactive thyroid.

Thyroiditis is an acute inflammatory disease of the thyroid, presumably caused by a virus, which comes in three phases, including:

1. Thyrotoxic phase: This phase is when the thyroid is inflamed and begins releasing too many hormones. It is typically an acute, viral-like illness characterized by neck pain symptoms. This phase usually lasts 4-6 weeks on average.

2. Hypothyroid phase: Excess hormones are released for the next few weeks or months. During this phase, the synthesis of new hormones ceases because the thyroid is damaged. Thyroid hormone levels are mildly or moderately low, and there may be an increase in thyroid autoantibodies, which contribute to chronic thyroid inflammation. This phase usually lasts 2-6 months on average.

3. Euthyroid phase: During this phase, the thyroid hormone levels normalize. As the inflammation subsides, the cells in the thyroid gland begin to regenerate, and hormone production and secretion can resume.

Toxic Multinodular Goiter (Plummer Disease)

Toxic multinodular goiter accounts for approximately 5-15% of cases⁶ of hyperthyroidism in the United States, second only to Graves’ disease.

This type of hyperthyroidism occurs when multiple nodules on the thyroid become autonomously hyperactive. Ultimately, individuals with toxic multinodular goiter will experience an enlarged thyroid gland with small, rounded nodules.

Who is most at risk of developing hyperthyroidism?

Several conditions and lifestyle factors can cause hyperthyroidism. The condition is most commonly caused by Graves' disease, various forms of thyroiditis, "hot" thyroid nodules, and in patients with underlying non-toxic nodular goiters.

With that said, various factors can increase a person's risk of developing hyperthyroidism. Being aware of these risk factors can help you be more proactive about your health and decrease your chances of developing hyperthyroidism. Factors like genetics, environmental, and individual health factors all play a role.

Here are the risk factors to know about:

Being female

Thyroid conditions, in general, appear to be more prevalent in women than in men (1).

Autoimmune disease

Having an autoimmune disease, including type 1 diabetes, increases a person's risk of developing some types of hyperthyroidism, such as Painless Lymphocytic Thyroiditis.

Family history

Having a family history of autoimmune thyroid disease. Research shows thyroid disease is more common in families with a history of some form of thyroid disease⁷ than those without it.

Summary of hyperthyroidism symptoms

Hyperthyroidism can cause various symptoms, which may be mild but can also intensify. Additionally, because the symptoms of hyperthyroidism can mimic other health problems, it's often difficult to get a diagnosis.

People with overt hyperthyroidism can experience anxiety, emotional lability (mood swings), weakness, tremor, heat intolerance, increased perspiration, and weight loss despite a normal or even increased appetite.

• Unintentional weight loss: An individual with hyperthyroidism may experience unintentional weight loss. Sometimes, people do not decrease their food intake or notice reduced appetite. In younger patients, the appetite may dramatically increase. However, weight loss still occurs.

• Rapid heartbeat: Also known as tachycardia, rapid heartbeat is generally more than 100 beats per minute. Some people can experience a thyroid storm, in which their heart rate, blood pressure, and body temperature become rapidly and highly elevated. If left untreated, thyroid storms can be fatal.

• Changes in bowel movements: An unusual change in bowel movements can be a sign of hyperthyroidism, especially if the bowel movements have become more frequent. 

• Enlarged thyroid gland: An enlarged thyroid gland can appear in people with hyperthyroidism, and it is noticeable at the front base of their neck.

• Other symptoms: Other symptoms associated with hyperthyroidism may include but are not limited to brittle hair, fatigue, muscle weakness, nervousness, tremors, and skin thinning. Older people may have symptoms similar to depression or dementia.

Treating hyperthyroidism

When determining treatment options, your doctor will consider a few factors, such as:

• Your age, overall health, and medical history

• The disease that is causing the hyperthyroidism

• The severity of the condition.

Some treatment options may include:

• Antithyroid drugs to lower the thyroid hormone levels

• The use of radioactive iodine to damage thyroid cells slows down thyroid production

• Surgery to remove some or all parts of the thyroid.

The lowdown

Hyperthyroidism involves a thyroid that overproduces hormones. It’s a condition that affects about 1.3% of the population. Women are more likely to developing it, and the risk of hyperthyroidism may increase with age.

The primary causes of hyperthyroidism include thyroiditis, toxic multinodular goiter, and Graves' disease.

Those living with hyperthyroidism may experience a variety of symptoms, including unintended weight loss, brittle hair, and changes in bowel movement. However, people can live a long and healthy life with the proper treatment.