The Thyroid: What is it and Why Does is Matter to Me?

While it may not receive the same amount of press as more well-known organs such as the heart or lungs, the thyroid gland serves a vital function through the secretion of thyroid hormone, a substance that is essential to life. Thyroid hormone exerts important effects on almost all organs in the body, and alterations in thyroid hormone levels or abnormal growths  in the thyroid can result in disease and health problems.

Anatomy of the thyroid

The thyroid is a butterfly-shaped organ that sits below the thyroid cartilage (commonly known as the “Adam’s pple”) and in front of the trachea. The thyroid is composed of a right and left lobe, and these lobes are connected by a bridge of thyroid tissue called the isthmus. Some people have a small amount of additional thyroid tissue called a pyramidal lobe, a remnant of tissue leftover from fetal development. In addition, four smaller parathyroid glands are typically embedded in the back of the thyroid gland. These glands do not directly affect thyroid function, but help control calcium levels in the body.

Iodine and the thyroid

Iodine, an essential trace element typically found in seafood, dairy products, and iodized salt, is an important ingredient in the formation of thyroid hormone. The U.S. Institute of Medicine recommends a daily intake of 150 micrograms a day of iodine for adults, with increased intake for pregnant or lactating women.

Low levels of iodine during pregnancy can be particularly harmful to the fetus and result in a condition called cretinism, which manifests through stunted physical and mental development. On the other hand, excessively high intake of iodine in children or adults can also result in thyroid dysfunction.

Hypothyroidism (Low Thyroid Function)

Low levels of thyroid hormone, also known as hypothyroidism, are associated with decreased metabolism and a generalized slowing of body functions. Symptoms and signs of hypothyroidism include weight gain, fatigue, slow heart rate, feeling abnormally cold, constipation, and dry skin. A number of conditions can cause low thyroid states, including Hashimoto’s thyroiditis, an autoimmune condition in which the thyroid loses function. While Hashimoto’s can affect both genders and all ages, it tends to be more in common in women. Hypothyroidism can be detected by simple blood tests and is typically treated with thyroid hormone replacement.

Hyperthyroidism (High Thyroid Function)

High levels of thyroid hormone, also known as hyperthyroidism, are associated with increased metabolism and a generalized quickening of body functions. Symptoms and signs of hyperthyroidism include weight loss, anxiety, fast heart rate, feeling abnormally hot, frequent bowel movements, and tremors. Conditions that  cause  yperthyroidism include Graves’ disease and subacute  thyroiditis (also known as De Quervain’s thyroiditis). Graves’ disease typically manifests as a uniformly enlarged thyroid gland, and can also result in eyes that appear to bulge out. While hyperthyroidism can be detected by blood tests, additional testing, including specialized tests to evaluate iodine uptake by the thyroid gland, may be needed to determine the cause of hyperthyroidism.

Thyroid nodules

Thyroid nodules are masses that form in the thyroid. They may be filled with cells, fluid, or a mixture of both. Statistically speaking, while most thyroid nodules are benign, a small portion of thyroid nodules can be cancerous. A fine needle aspiration (FNA), in which thyroid cells are removed through a small needle inserted into the skin, is often performed to determine the cellular makeup of thyroid nodules and evaluate for thyroid cancer. Most benign thyroid nodules can be observed – however, a benign nodule may be surgically removed if it results in compressive symptoms (such as difficulty swallowing). Thyroid cancer is typically treated with surgery and thyroid hormone replacement.Radioactive iodine (RAI) treatment is also often used to treat thyroid cancer after surgery.

Why does it matter to me?

Thyroid abnormalities, particularly alterations in thyroid hormone levels, are common and can affect both genders. While symptoms of hypothyroidism and hyperthyroidism can be found in a wide range of conditions, if you experience such symptoms, speak to your doctor. Low or high levels of thyroid hormone are easy to detect and diagnosis starts with a simple blood test to measure them. Maintaining normal thyroid levels during pregnancy is also important to optimizing maternal and fetal health. In addition, if you notice or feel lumps in the area of your thyroid, speak with your doctor to discuss if any further evaluation is warranted.

References:

American Thyroid Association. “Iodine Deficiency.” June 2012.

Retrieved from www.thyroid.org/iodine-deficiency.

American Thyroid Association. Thyroid Nodules. 2012. Retrieved from  www.thyroid.org/wpcontent/uploads/patients/brochures/Nodules_

brochure.pdf.

National Institutes of Health Office of Dietary Supplements. “Iodine

Fact Sheet for Consumers.” June 2011. Retrieved from

ods.od.nih.gov/factsheets/Iodine-QuickFacts.