Hyperthyroidism 101: What Happens When Your Thyroid Stops Functioning Properly?

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Once a little-known part of the body, the thyroid has gained much attention in recent years, mainly because it plays such an important role in how well the body’s metabolism works. When the thyroid isn’t functioning properly, it can lead to numerous problems, including hyperthyroidism. We’ll discuss this condition in depth in observance of Thyroid Awareness Month.

What Is the Thyroid?

The thyroid is a small, butterfly-shaped gland located in the neck, in front of the windpipe. It is responsible for producing the hormones triiodothyronine (T3) and thyroxine (T4). The T3 and T4 hormones control the body’s metabolism — how every cell in the body uses energy. 

Hyperthyroidism, also known as an overactive thyroid, is what happens when the thyroid produces too much of these thyroid hormones. Slightly more than 1% of Americans are affected by hyperthyroidism. Although hyperthyroidism can affect people of all genders, it’s about 10 times more common in women than men, and usually appears between the ages of 20 and 40 years.

Symptoms Associated With a Thyroid That’s Not Functioning Properly

When the thyroid doesn’t function properly, a variety of problems can occur, from weight fluctuations to fertility issues. A number of symptoms are associated with hyperthyroidism but many of them are nonspecific and common in other conditions, which may make the diagnosis challenging for doctors. 

Some symptoms of hyperthyroidism are listed below:

  • Weight loss
  • Trouble concentrating
  • Trouble sleeping
  • Being overly sensitive to heat
  • Irregular periods
  • Fatigue
  • Frequent bowel movements or diarrhea
  • Goiter (enlarged area at the base of the neck)
  • Increased appetite
  • Increased sweating or clammy skin
  • Restlessness
  • Nervousness
  • Hair loss or thinning
  • Protruding eyes Note: This occurs in Graves’ disease, a specific cause of hyperthyroidism.
  • Hand tremors
  • Elevated blood pressure
  • Rapid heart beat
  • Breast development in men
  • Osteoporosis

What Causes a Change in Thyroid Function?

A number of factors can affect how well the thyroid functions, including:

  • Graves’ Disease: This is an autoimmune disease that causes the thyroid to overproduce thyroid hormones. It is the cause of more than 80% of cases of overactive thyroid. Graves’ disease is hereditary (passed down through a family). If a member of your family has Graves’ disease, there’s a chance others in the family could have it too. It’s more common in women than men. Graves’ disease is the most common cause of hyperthyroidism.
  • Toxic Adenoma: Also called Plummer disease or toxic multi-nodular goiter, these are non-cancerous growths on the thyroid that cause it to enlarge and produce too much T4 hormone.
  • Thyroiditis: This is an inflammation of the thyroid and it can occur for a number of reasons, including some viral infections. Often the reason is not known.
  • Pituitary Problems: Problems with the pituitary gland can result in poor regulation of the thyroid gland. All parts of the endocrine system in the body works closely together, so if something is wrong with one part, problems can develop in others.
  • Too Much Iodine: Iodine is found in many green leafy vegetables, but its richest source is sea kelp and other seaweeds. An iodine derivative is also added to table salt.
  • Overmedicating an Underactive Thyroid: This is simply an overdose of thyroid hormone.
  • Tumors: These can occur on the ovaries or testes and can affect the thyroid’s hormone production.
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Diagnosing Hyperthyroidism 

Testing for hyperthyroidism is as simple as drawing some blood. A doctor can run a thyroid panel, which will measure the levels of thyroid hormones. A person with hyperthyroidism will typically show the following results:

  • low in thyroid-stimulating hormone (TSH)
  • high in T3 and free T4

However, doctors are discovering that even if a person’s results are within a “normal” range, the range is so broad that there could still be a problem. Also, not all doctors are familiar with thyroid problems or with interpreting the test results. This can lead to a person with hyperthyroidism being repeatedly misdiagnosed or disregarded by their doctor altogether.

Taking a vitamin called biotin or a multivitamin with biotin can cause false results on the thyroid panel, so let your doctor know if you’re taking biotin or stop taking it for a few days before your thyroid blood test.

The normal range for thyroid hormones is very broad and may vary between countries and laboratories:

  • T4 = 5.6–13.7 micrograms per deciliter (μg/dL or mcg/dL)
  • Free T4 = 0.8–1.5 nanograms per deciliter (ng/dL)
  • T3 = 87–180 ng/dL
  • Free T3 = 230–420 picograms per deciliter (pg/dL)
  • TSH = 0.4–4.5 milli-international units per liter (mIU/L or mU/L)

Because these ranges are so broad, a problem can still exist even if a person is within the “normal” range. Some endocrinologists will treat a person whose T3 or T4 levels are at the high end of normal.

A physical examination might also help in the diagnosis of hyperthyroidism, as some of the signs can be obvious such as:

  • Tremor in the fingers
  • Overactive reflexes
  • Warm, moist skin
  • Enlarged, bumpy thyroid
  • Rapid or irregular pulse
  • Eye changes

In some cases, you may also require an ultrasound examination of your neck.

Treating Hyperthyroidism

Treatment for hyperthyroidism is usually quite simple. Several medications that are available by prescription will decrease the amount of T4 and T3 that the thyroid produces. Like all medications, they can have some side effects, so be sure to discuss the pros and cons of these treatments with your doctor. 

A medication called a beta-blocker, which is usually used to treat heart problems, might be prescribed; although it doesn’t treat hyperthyroidism, it can help some of the symptoms such as palpitations and tremor. Medication will generally return your thyroid hormone levels to normal within 12 weeks or so, with relief of most symptoms. After this, you may have to take medications to maintain normal levels of hormones.

Another treatment option is radioactive iodine. Radioactive iodine is absorbed by the abnormal cells in the thyroid that are overproducing the hormones. This will eventually cause the cells to die and the thyroid to return to normal, although this type of treatment can result in hypothyroidism, a condition in which the thyroid doesn’t produce enough hormones. If you develop hypothyroidism, you would need to take medications to increase your levels of T3 and T4 to normal. Radioactive iodine is used in about 70% of cases of hyperthyroidism and is considered safe.

Surgery to remove the thyroid gland entirely is also an option. However, once the thyroid is removed, you will need to take replacement thyroid hormones for the rest of your life. Choosing surgery should be carefully considered because there are inherent risks associated with any surgical procedure.

Overall, hyperthyroidism is a treatable condition, but it can cause other serious problems, such as heart problems or infertility if it is ignored. If you suspect you have a thyroid problem, see your doctor promptly for testing.