The thyroid gland produces the hormones T4 (thyroxine or tetraiodothyronine), T3 (triiodothyronine) and calcitonin and secretes them into the bloodstream where they are distributed to all parts of the body. These hormones are responsible for vital functions like controlling the amount of oxygen that cells utilize and how cells and organs convert nutrient into energy.

Cindy Samet, a chemistry professor at Dickinson College in Carlisle, Pennsylvania explained the vital role of the thyroid gland in the body: “…the thyroid gland is the body’s master metabolic control center. Brain, heart and kidney function, as well a body temperature, growth and muscle strength—and much more—are at the mercy of thyroid function.”

The thyroid is also responsible for regulating brain and nerve function as well as the function of the hair, skin, heart, eyes and intestines.

Thyroid diseases are some of the most prevalent medical conditions in the world and studies have revealed that while they are most prevalent in areas of the world where there is a high rate of iodine deficiency in the diet.

Signs and symptoms may also vary from area to area as well as the availability of treatments.

With the growing number of people suffering from thyroid diseases, there have been major international efforts to help areas most affected by these medical conditions to address iodine deficiency by increasing iodine intake. In fact, some countries have recommended the mandatory iodization of salt, which is an essential condiment in most households.

The World Health Organization also recommends an ideal iodine dietary allowance of at least 150 micrograms of iodine/day. This number increases to 250 micrograms in pregnant women and 290 micrograms for lactating mothers.

According to WHO, there are at least two billion people suffering from iodine deficiency, 285 million of which are school-age children.

A urinary excretion of less than 100 micrograms per liter can have significant effects on a child’s growth and development, which often results in one of the most common preventable mental impairments around the world.

According to Dr. Hershman, “women are particularly at risk for a thyroid issue. One in eight women will develop a thyroid disorder during the course of their lives—that’s five to eight times the rate in men.” Individuals also become more susceptible for thyroid diseases due to the following risk factors:

Thyroid cancer is another known condition that affects the thyroid. According to a study published in the Journal of the American Medical Association (JAMA) in 2017 revealed that between 1975 and 2013, there has been a steady growth of thyroid cancer cases around the world. According to Dr. Melanie Goldfarb, an endocrine surgeon and director of the Endocrine Tumor Program at Saint John’s Health Center in California, “up to 70 percent of middle-age females and 40 to 50 percent of middle-age males have thyroid nodules.”

Common causes

While an individual is at a higher risk for contracting thyroid diseases with all the risk factors mentioned above, they are commonly caused by medical conditions that affect the functions of the thyroid gland:

Hypothyroidism

It is essentially a condition in which the thyroid gland does not produce enough thyroid hormone due to under activity.

In turn, it causes the body’s metabolism to run slower than normal, which results to sudden weight gain, dry hair, fatigue, dry skin, hair loss, low tolerance to cold, constipation, memory loss and abnormal menstrual cycles.

According to studies, there are at least 10 million Americans who have hypothyroidism and 10% of women may have this condition to some degree with some not even knowing that they have it.

Hashimoto’s thyroiditis

Also known as Hashimoto’s disease, this autoimmune disease is the most common cause of hypothyroidism. With Hashimoto’s thyroiditis, your immune system attacks your thyroid causing significant damage to it, which in turn affects its ability to produce enough thyroid hormones that your body requires.

Your risk of developing this condition is higher if you are suffering from other autoimmune disorders like autoimmune hepatitis, Addison’s disease, pernicious anemia, lupus, Type 1 diabetes and vitiligo.

Hashimoto’s disease is the most common cause of hypothyroidism in Americans affecting 5 in 100 people. It is also eight times more common in women than in men and symptoms often appear between the age of 40 and 60. Hashimoto’s thyroiditis causes weight gain, low tolerance to cold, constipation, fatigue, dry hair and even depression.

Hyperthyroidism

Hyperthyroidism is a condition where the thyroid gland produces too much of the thyroxine hormone, which accelerates the body’s metabolism and result to unintentional weight los, tachycardia or rapid heart rate, increased appetite, tremors, sweating, anxiety and increased sensitivity to heat.

Graves disease is the most common cause of hyperthyroidism, but thyroiditis or the swelling of the thyroid gland or hyper functioning thyroid nodules can also cause it.

Compared to hypothyroidism, only 1.2% or 1 in 100 people in the United States who have hyperthyroidism.

Graves’ disease

Graves’ disease is a type of autoimmune disorder that causes an overactive thyroid. Like Hashimoto’s thyroiditis, Graves’ disease causes the immune system to attack the thyroid, which makes it produce more thyroid hormones than the body requires.

Since thyroid hormones are responsible for controlling the rate in which your body utilizes energy, this deficiency can affect almost every organ in your body including the way your heart beats.

Graves’ disease is the most common cause of hyperthyroidism among Americans affecting 1 in 200 people.

Goiter

A goiter is essentially the abnormal enlargement of the thyroid gland that could eventually affect the way you cough, swallow or breathe, although it is painless. Goiter is commonly caused by the lack of iodine in the diet, which is why WHO has recommended the voluntary or mandatory iodization of salt.

In the United States where iodized salt is used in every household, goiter is caused either by thyroid nodules, hypothyroidism or hyperthyroidism.

Some of the symptoms of goiter include a noticeable swelling at the base of the neck, coughing, a tight feeling in the throat and eventually, difficulty in swallowing and breathing as the thyroid gland enlarges further.

Thyroid nodules

A thyroid nodule is essentially a lump or swelling in the thyroid gland. Most of these nodules are harmless, but in some instances, they could cause the overproduction of thyroid hormones or they could be cancerous.

According to Dr. Melanie Goldfarb, director of the Endocrine Tumor Program at Providence Saint John’s Health Center in California, “up to 70% of middle-age females and 40 to 50 percent of middle-age males have thyroid nodules. You can also be born with an extra piece anywhere as high up as the base of your tongue.”