An Overview of the Thyroid Gland: What it is & How it Works

Our heart, brain, liver, kidneys, and skin all rely on one tiny, often-overlooked, butterfly-shaped gland: our thyroid. Located just under our voice box, this little workhorse regulates several body functions and plays more roles in our bodies than you may realize.

While some of us have likely never given it a second thought, nearly 20 million Americans today have some form of thyroid dysfunction or disease. Women are particularly affected, accounting for five to eight times more cases than men.

Fortunately, most of these conditions are fairly easy to treat. However, up to 60% of people with thyroid problems are unaware that they have them and undiagnosed disorders of the thyroid gland put us at risk for a number of serious conditions.

Although January is National Thyroid Awareness Month, it's essential to gain a better understanding of how the thyroid works, identify the symptoms of common thyroid-related issues and diseases, and learn about testing and treatment options every month of the year.

What Is the Thyroid Gland?

The thyroid gland is a butterfly-shaped endocrine gland normally located in the lower front of the neck.

What is the function of the thyroid gland?

The thyroid's job is to make hormones that are secreted into the blood and then carried to every tissue in the body. The thyroid hormone helps the body use energy, stay warm, and keep the brain, heart, muscles, and other organs working as they should.

How Does the Thyroid Gland Work?

The thyroid gland secretes the hormone T4 which contains four iodine atoms. Then, T4 is converted to T3 by the removal of an iodine atom. This occurs mainly in the liver and in certain tissues where T3 acts, such as in the brain. The amount of T4 produced by the thyroid gland is controlled by the thyroid stimulating hormone (TSH), which is made in the pituitary gland located at the base of the brain.

From there, the amount of TSH that the pituitary sends into the bloodstream depends on the amount of T4 that the pituitary sees. For example, if the pituitary sees very little T4, then it produces more TSH to tell the thyroid gland to produce more T4. Once the T4 in the bloodstream goes above a certain level, the pituitary's production of TSH is shut off.

This seems very complicated, but it's not.

Think of the thyroid and pituitary as a heater and a thermostat. When the heater (thyroid gland) is off and it becomes cold, the thermostat (pituitary gland) 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. Thus, the thyroid and the pituitary, like a heater and thermostat, turn on and off. This feedback loop keeps the levels of T4 in the blood stable and reacts to small changes immediately.

Hyperthyroidism vs. Hypothyroidism

Typically the thyroid gland produces the exact number of hormones needed to keep the body's metabolism running and in balance.

As described above, the TSH secreted by the pituitary gland remains constant in blood circulation, but its levels may increase or decrease when T4 levels in the blood change. However, several disorders are associated with the thyroid gland with most problems concerning the production of thyroid hormones.

Either the thyroid gland produces too much hormone (called hyperthyroidism) or your thyroid doesn't produce enough hormone (called hypothyroidism), resulting in your body using energy faster or slower than it should.

5 Ways to Know if I Have a Thyroid Problem

If you're experiencing any of the following symptoms, it may be time to get your thyroid checked. Here are the 5 ways to know if you have a thyroid problem:

1. Mood changes
2. Changes in sleep
3. Difficulty regulating temperature
4. Missed period (without pregnancy)
5. Significant weight changes (with no change in routine)

1. Mood Changes

Symptoms of hyperthyroidism may include anxiety, nervousness, and irritability, while symptoms of hypothyroidism may include depression.

2. Changes in Sleep

Hyperthyroidism can cause difficulty falling asleep at night, which can lead to fatigue, while the lack of thyroxine in hypothyroidism can drain your energy. Both hypo & hyperthyroidism can also cause muscle weakness, leading to feelings of tiredness.

3. Difficulty Regulating Temperature

Hyperthyroidism can cause sensitivity to heat and excessive sweating, while hypothyroidism can lead to difficulty keeping warm. The changes in hormone levels associated with thyroid disease can confuse the body into producing too much heat and not enough energy or the other way around.

4. Missed Period (Without Pregnancy)

Thyroid issues can lead to a missed period due to the disruption of hormones caused by thyroid dysfunction. Too much or too little of the hormone thyroxine can cause an abnormal menstrual cycle or even a complete cessation of menstruation. When this happens, it's referred to as hypothyroid amenorrhea. This condition is usually associated with other signs and symptoms, such as fatigue, weight gain, hair loss, dry skin, constipation, and decreased libido.

5. Significant Weight Changes (With No Change in Routine)

Too much or too little of the hormone thyroxine can cause an abnormally slow metabolism, resulting in difficulty losing or gaining weight. This can result in either rapid and unexpected weight gain or rapid and unexpected weight loss.

Take Care of Your Health

Thyroid disease can lead to serious health implications and it's essential to recognize the symptoms of poor thyroid function early.

If you experience fatigue, abrupt weight changes, or any of the other aforementioned symptoms, schedule an evaluation and tests with your doctor. With early diagnosis and treatment, you can protect your long-term health and well-being.

Editor's Note: This blog was originally published on 1/01/2021 and was updated on 8/14/2023.