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The thyroid gland is a spongy butterfly-shaped tissue that sits over the windpipe, just above the collarbones. Its primary job is to make thyroid hormones, which are released into the bloodstream and are taken to various body cells.
Thyroid hormones are responsible for controlling the speed at which the body works, including how awake you are, how quickly your brain works, how fast does your gut digests food, how quickly your skin regenerates, how fast your hair grows, and how fast you metabolize medications, drugs, and other hormones.
They play a critical role in skeletal and sexual development along with various essential body functions. Given the wide-reaching impact of thyroid hormones, any form of thyroid dysfunction will adversely impact different organs and its symptoms can be felt in different parts.
How Common Are Thyroid Disorders?
Thyroid problems are quite common. Studies suggest 10% or more of the general population may have some form of thyroid disease or dysfunction. (1)
Different Types of Thyroid Disorders
There are many types of thyroid problems:
- Problems with the function of the thyroid – The thyroid gland can make too much or not enough thyroid hormones.
- Problems with the structure of the thyroid – Nodules can develop in the thyroid. Most of those nodules are benign, but a small percentage can be thyroid cancer.
- A link between problems with thyroid function and problems with thyroid structure
What Is Meant by an Overactive and Underactive Thyroid?
An overactive thyroid makes and releases too much thyroid hormones. The condition is also called hyperthyroidism. An underactive thyroid makes and releases too little thyroid hormones. The condition is also called hypothyroidism.
General Causes of an Overactive and Underactive Thyroid
Overactive thyroid
There are four main causes of an overactive thyroid:
- Grave’s disease is an autoimmune disease where the body makes antibodies that stimulate the thyroid to pour out thyroid hormone. This is the cause of hyperthyroidism, which causes protrusion of the eyes that is so often associated with the condition.
- Thyroiditis is a temporary hyperthyroidism often caused by viruses (including COVID-19). It lasts for 4–6 weeks and then can lead to an underactive thyroid, but ultimately resolves on its own.
- Benign thyroid nodules can produce excess thyroid hormones.
- Hashimoto’s disease can cause a temporary hyperthyroidism that is usually quite mild.
Underactive thyroid
The most common cause of an underactive thyroid is Hashimoto’s disease. (2) It is an autoimmune disease in which infection-fighting white blood cells attack the thyroid and cause inflammation and breakdown of thyroid cells.
The thyroid cannot regenerate, and when enough thyroid tissue is destroyed, the thyroid can no longer make adequate amounts of thyroid hormones.
Many patients with a hypothyroid have had part or all of their thyroid removed to treat either thyroid cancer or Grave’s disease. Radioactive iodine, a common treatment of Grave’s disease, also leads to an underactive thyroid.
Less commonly, patients exposed to radiation, either as cancer treatment or due to accidents such as the Chernobyl disaster, can develop an underactive thyroid even many years after they are exposed.
Symptoms of an Overactive Thyroid and Underactive Thyroid
All the symptoms of an overactive thyroid are the result of speeding up the body, which include:
- Trouble sleeping
- Talking quickly and feeling anxious
- Rapid heart rate even when sitting still, which can lead to an abnormal heartbeat (3)
- A gut that works overtime, which can lead to increased appetite, frequent bowel movements, diarrhea, and weight loss despite eating more (4)
- In women, very light or absence of periods
All the symptoms of an underactive thyroid are the result of slowing the body down, which include:
- Feeling tired and sluggish even after getting an adequate amount of sleep
- Trouble with memory and foggy thinking
- Slow heartbeat, causing less blood flow to the kidneys and consequently water retention
- Slowing down of the gut, leading to decreased appetite, constipation, and weight gain despite eating less (4)
- In women, frequent and heavy periods
Treatment for an Overactive and Underactive Thyroid
The treatment for thyroid problems depends upon the source of the problem.
Treatment for an overactive thyroid
The treatment for an overactive thyroid depends upon the cause:
- Many causes of hyperthyroidism will get better on their own.
- Antithyroid medications, which block the production and release of thyroid hormones, can be used to treat patients with Grave’s disease or hyperfunctioning nodules. (5)
- Treatment with radioactive iodine to ablate the thyroid or hyperfunctioning nodules can often be helpful.
- In some cases, surgery to remove part or all of the thyroid may be indicated.
Patients with an overactive thyroid should see an endocrinologist for the proper diagnosis and treatment.
Treatment for an underactive thyroid
The treatment for an underactive thyroid is more straightforward. In almost every case, the appropriate treatment is supplementation of thyroid hormones with a medication called levothyroxine. (6)
Levothyroxine does not fix the problem with the thyroid. It simply replaces the thyroid hormone the body would make if it could, but cannot, whatever the cause of hypothyroidism.
Some people will need levothyroxine for a short time, but most patients will need to take thyroid hormones for the rest of their lives.
Role of Diet in Treating Thyroid Dysfunction
I do not routinely recommend dietary changes in patients with overactive or underactive thyroid. Occasionally, patients with an overactive thyroid should avoid foods high in iodine such as seafood.
Similarly, there are some patients with underactive thyroids who may benefit from iodine supplementation. But in most developed countries, low iodine levels are not a significant factor in hypothyroidism.
Doctor’s Observation About Patients With Thyroid Problems
All patients have a symptom that they notice that tells them if their thyroid is in balance. For some patients, it is their mood; for others, their endurance when exercising; and for others, their periods or resting heart rates.
I have learned to listen when patients have these symptoms; their labs often reflect what they feel.
Final Word
The symptoms patients feel when they first have an underactive or overactive thyroid are temporary. With treatment, most patients return to feeling like and looking like themselves.
Even though many types of thyroid disease are lifelong, most patients find treatment to be effective and easy. Patients with an underactive thyroid can often be well managed by their general practitioner. However, patients with an overactive thyroid should always be seen by a specialist for the proper diagnosis and management.
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