What Does Your Thyroid Do?

Medically Reviewed by Carol DerSarkissian, MD on May 28, 2023
2 min read

The thyroid is a 2-inch-long, butterfly-shaped gland in the front of your neck that controls your metabolism. It’s part of your endocrine system, which makes chemicals called hormones that help control many of your body’s functions.

The thyroid sits just below your voice box (larynx), near the base of your neck. Two hormones made by the thyroid gland help regulate your metabolism -- the chemical processes in your body that break down what you eat to make energy. They can affect how fast your heart beats, how deep you breathe, and whether you gain or lose weight. They can also help control your body temperature, cholesterol levels, and women’s menstrual cycles.

Doctors call these hormones T-3 and T-4 for short. The thyroid releases them into your bloodstream, which takes them through your body. Another gland, called the pituitary gland, tells your thyroid how much of these hormones your body needs.

Sometimes, the thyroid gland develops a problem. It might start producing too much or too little hormone. It might become enlarged, or it could grow lumps of extra tissue.

More than 12% of people will have some sort of problem with their thyroid during their lifetime. Women are far more likely to have this happen than men.

Common thyroid problems include:

Hypothyroidism. This occurs when your thyroid doesn’t make enough hormones. That slows your metabolism. It can make you gain weight and feel sluggish or depressed. Sometimes that’s caused by a condition called Hashimoto’s disease. This happens when your body’s disease-fighting immune system attacks the thyroid.

Hyperthyroidism. If you’re feeling irritable, losing weight, your heart races, and you’re feeling weak, your thyroid might be producing too much hormone. This is often the result of another immune system problem, known as Graves’ disease, but can be caused by other conditions as well.

Goiters. A goiter happens when your thyroid gland swells up. Sometimes, it makes a noticeable bulge in your neck; other times, it can make you cough or make your voice sound hoarse. A goiter can be caused by other thyroid conditions or by a lack of iodine, an element your thyroid needs to work properly. Most Americans get plenty of iodine because it’s now added to table salt in the United States.

Nodules. These are growths on the thyroid gland. Sometimes, they can cause the thyroid to make too much hormone -- and in some cases, they turn out to be cancerous.

If you’re experiencing any of these things, talk to your doctor. They can order some tests to help pinpoint the problem and discuss ways to treat it.