The thyroid is a small gland that helps regulate a person’s metabolism by producing hormones.

A person can develop problems if their thyroid overproduces or underproduces hormones. These states are known as hyperthyroidism and hypothyroidism, respectively.

Changes in hormone production may also result in the thyroid gland swelling to a visible, enlarged state called a goiter.

Researchers estimate that about 13 million people have an undiagnosed thyroid illness in the United States.

This article looks at the different types of thyroid disorders, what causes them, their symptoms, and how doctors diagnose and treat them.

Share on Pinterest
triocean/Getty Images

Hypothyroidism is when a person’s thyroid does not produce enough thyroid hormone. Not having enough thyroid hormone can slow down a person’s metabolism and lead to several adverse symptoms.

Hypothyroidism is more prevalent in birth-assigned females and is more common than hyperthyroidism.

Causes

Causes of hypothyroidism include:

The most common cause of hypothyroidism is Hashimoto’s thyroiditis. This is a condition in which a person’s immune system attacks their thyroid gland. The gland then becomes inflamed, and hormone production falls.

The exact cause of Hashimoto’s thyroiditis is unclear, but heredity may play a role. If a person has close family members with the condition, their risk of developing it can be greater.

Having another autoimmune disorder, such as rheumatoid arthritis, type 1 diabetes, or lupus, also increases the risk for Hashimoto’s.

Development of the disease can be prolonged, occurring over months or even years.

Symptoms

Hypothyroid symptoms can vary, but may include:

A person may also develop a goiter, or enlargement of the thyroid gland. This condition occurs when the gland tries to compensate for the lack of thyroid hormone.

Diagnosis

After discussing a person’s symptoms and family history, a doctor may perform a physical exam. This exam can include checking the thyroid gland area for swelling, measuring the patient’s heart rate, and checking their reflexes.

Doctors may also carry out blood tests as part of the diagnosis. These will assess levels of the thyroid-stimulating hormone (TSH) and thyroxine in a person’s blood.

Thyroxine is a hormone released by the thyroid gland. Low levels of thyroxine in the blood indicate hypothyroidism.

The body releases TSH to signal the thyroid gland to release thyroid hormones. When the body senses low thyroid hormone levels, it releases more TSH, so a high level of TSH typically indicates hypothyroidism.

Treatment

There is no cure for hypothyroidism, but a person can manage the condition with thyroid hormone replacement. A person typically takes thyroid hormone replacement daily as an oral pill.

Hyperthyroidism is when a person has too much thyroid hormone in their body. This can speed up their metabolic processes. A person with a heightened metabolic rate may experience a raised heart rate, high blood pressure, and fatigue.

Causes

The most common cause of hyperthyroidism is Graves’ disease.

In Graves’ disease, the immune system creates antibodies that signal the thyroid gland to grow and produce significantly more thyroid hormone than the body needs.

It is not clear why people develop Graves’ disease, although researchers believe that genetics plays a role.

Another cause of hyperthyroidism is multinodular goiter. This condition results from hormone-producing nodules in the thyroid gland becoming enlarged and releasing excess thyroid hormone.

Multinodular goiter is one of the most common thyroid gland disorders and is more prevalent in birth-assigned females than birth-assigned males.

A person may also experience an increase in thyroid hormone levels without the thyroid gland itself being overactive.

Thyroiditis is a temporary inflammation of the thyroid gland due to an autoimmune condition or a virus. This may temporarily cause thyroid hormone to leak into the blood without the gland overproducing.

A person taking hormone replacement medication to treat an underactive thyroid may also experience an increase in thyroid hormone levels.

Symptoms

Common symptoms of hyperthyroidism can include:

  • fatigue and muscle weakness
  • rapid or irregular heartbeat
  • tremors in the hands
  • problems sleeping
  • nervousness
  • irritability
  • frequent bowel movements
  • unintended weight loss
  • a light menstrual flow or fewer periods

Diagnosis

Doctors will primarily use blood tests to diagnose hyperthyroidism. However, before this, they may look for physical symptoms including a visibly enlarged thyroid, a rapid pulse, and tremors in the fingers.

As with hypothyroidism, blood tests will primarily measure thyroid hormone and TSH levels.

In a person with hyperthyroidism, the amount of thyroid hormone in the blood will be higher than usual, and in turn, the body will release less TSH. A doctor may diagnose the condition if tests reveal both of these results.

Treatment

A doctor may recommend beta-blockers as a short-term treatment for hyperthyroidism. Beta-blockers stop some of the effects of the thyroid hormone and can reduce symptoms such as a rapid pulse and tremors.

According to the American Thyroid Association, a doctor may also suggest a more permanent treatment including:

  • Antithyroid drugs: These drugs can stop the thyroid from making so much thyroid hormone.
  • Radioactive iodine tablets: When a person ingests these tablets, thyroid cells absorb the iodine. This treatment then destroys them, and the gland’s hormone overproduction stops.
  • Surgery: A surgeon may remove a part, or all, of a person’s thyroid.

If a person takes radioactive iodine or undergoes surgery, their thyroid may no longer produce enough hormones, and they may develop hypothyroidism. In this instance, they would then require thyroid hormone replacement treatment.

Thyroid nodules are lumps on a person’s thyroid and can appear alone or in groups.

Thyroid nodules are common. Around 50% of people over 60 years of age have a thyroid nodule, according to estimates. However, the vast majority of thyroid nodules are harmless.

It is not clear why people develop thyroid nodules. Thyroid nodules do not typically cause symptoms, although in some cases, they may cause hyperthyroidism by becoming overactive.

A doctor will be able to feel thyroid nodules on a person’s neck during an examination. If they discover nodules, they may check for hyperthyroidism or hypothyroidism.

A 2015 report states that thyroid cancer is present in 7-15% of thyroid nodule cases. During diagnosis, doctors may perform an ultrasound or a fine-needle biopsy to check for cancer.

If there are any signs of cancer or possible cancer risk in the future, a doctor will recommend removing the nodules. Depending on the type of cells found in a biopsy, and the risk of the nodule being cancer, a doctor may remove part or all of the gland.

The thyroid gland is responsible for producing hormones that regulate the body’s metabolism.

There are many different thyroid disorders, but doctors typically categorize them into those that make the thyroid produce too much or too little of these hormones.

Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone. This speeds up a person’s metabolism and can result in an increased heart rate, high blood pressure, and fatigue.

Conversely, hypothyroidism is when the thyroid gland produces too little hormone. This lowers the body’s metabolism and can lead to tiredness, feelings of cold, and constipation.

Thyroid nodules can appear on the thyroid gland alone or in groups, and are common in older adults. These nodules can cause hyperthyroidism and may include cancerous cells.

If a person is concerned that they may have a thyroid disorder, they should speak to a doctor about testing.