The Engine Powering Your Body: Thyroid Health & Importance

The thyroid plays an important role in your body, but if you’re like most people you probably are unaware of what it actually does or even where it is. As part of the endocrine system, this two-inch-long, butterfly-shaped gland makes hormones that help control many bodily functions, and serves as your body’s “engine.”

Located at the base of one’s neck, just below the larynx, the thyroid produces hormones that are then secreted into the bloodstream and carried to every tissue in the body. These hormones help regulate metabolism, affect how fast the heart beats, how deeply one breathes, can impact one’s weight (loss/gain), help the body use energy, stay warm, and keep organs working correctly.

T3 and T4 Hormones

The hormones secreted by the thyroid are called T3 and T4. Thyroxine, the major hormone secreted, is aptly referred to as T4 since it contains four iodine atoms. T4 is converted to T3 (triiodothyronine) by removing an iodine atom, mainly in the liver and brain.

The amount of T4 produced is determined by the pituitary gland, which produces another hormone called thyroid stimulating hormone, or TSH. If there is little T4 in the bloodstream, more TSH will be produced, signaling the thyroid to produce more T4. According to the American Thyroid Association, one can think of the thyroid and pituitary gland acting similar to a heater and thermostat. “When the heater (thyroid) is off and it becomes cold, the thermostat (pituitary) reads the temperature and turns on the heater. When the heat rises to an appropriate level, the thermostat senses this and turns off the heater.”

Many things impact the thyroid’s function. Even the slightest change could impact one’s body greatly. Depending on the level of hormones produced, an imbalance can lead to thyroid disease. About 20 million people in the United States have some form of thyroid disease, but it commonly goes unnoticed due to the absence of symptoms.

Hyperthyroidism and Hypothyroidism

When the thyroid produces too much hormone, it is considered to be hyperthyroidism. In this case, every bodily function may tend to speed up, which may lead to nervousness, irritability, increased sweating, racing heart, anxiety, difficulty sleeping, and muscle weakness.

A common form of hyperthyroidism is Graves’ Disease. This is caused by antibodies in the blood that turn on the thyroid and cause it to grow and secrete too much hormone.

On the other end of the spectrum, when the thyroid produces too little hormone, it is considered hypothyroidism. An underactive thyroid does not make enough hormone to keep the body running normally, so bodily processes begin to slow. When this happens, one may start feeling colder, getting tired more easily, and skin may become drier among other symptoms.

Common causes of hypothyroidism are autoimmune disease (Hashimoto’s thyroiditis), surgical removal of the thyroid (thyroidectomy), and radiation treatment.

Other Issues

  • Goiters: When the thyroid swells, a goiter may develop. These can make a noticeable bugle in one’s neck or cause a hoarse voice/cough. Goiters are caused by other conditions or by a lack of iodine.
  • Nodules: Growths on the thyroid sometimes cause the gland to make too much hormone; can sometimes be cancerous.


Because symptoms vary so much, nearly 60% of people are unaware that they have some form of the disease. The only way to know for sure is with a blood test to evaluate thyroid function. Common tests include:

  • TST: Determines the level of thyroid stimulating hormone (TSH) in the blood. Changes in TSH can provide an early warning signal before hormone levels actually change. A high TSH level indicates the thyroid isn’t making enough hormone (hypothyroidism), while a low TSH level indicates the thyroid is making too much hormone (hyperthyroidism). In most cases, a normal TSH value indicates proper thyroid function.
  • T4: There are a couple of different tests to measure T4 hormone levels.
    • Total T4 measures the bound and free hormone and can change when binding proteins differ.
    • Free T4 measures what is not bound and able to enter and affect the body’s tissues. Tests measuring free T4 more accurately measure how the thyroid gland is functioning when checked with a TSH.
  • T3: Useful when diagnosing hyperthyroidism and determining the severity of the disease. Patients with hyperthyroidism will have an elevated T3 level.
  • Thyroglobulin: Thyroglobulin is a protein produced by both normal and cancerous thyroid cells. Tg is not a measure of thyroid function and is instead most often used in patients who have had a thyroidectomy to monitor them after treatment.


Each January is Thyroid Awareness Month. While often an afterthought for one’s health, the importance of the thyroid cannot be understated. Raising awareness about the “engine” of the body is important for all. The American Thyroid Association has great information regarding testing and awareness events to consider.

My One Medical Source® (MOMS) is a compliant and convenient solution to increase access to testing by connecting those who need it with those who supply it. For more information contact us today.


**Medically reviewed by Dr. Sona Kirpekar, MD

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