The thyroid gland — a small butterfly-shaped gland found below the larynx — is part of the endocrine system. As a member of this system, the thyroid gland produces and regulates some aspects of hormone production in the body, specifically the production of triiodothyronine (T3) and thyroxine (T4).
The hormones the thyroid gland produces handle metabolic function and the development of the human body. Also, the thyroid helps to regulate mood, so if it is not operating correctly, a person may experience anxiety or depression.
For such a small gland, unnoticeable by touch, the thyroid is invaluable. The body depends on the gland's proper function to regulate its metabolic rate, contributing to muscle, heart, and digestive function, bone maintenance, and brain development.
Your Brain Runs the Show, Usually
The thyroid does not act alone; it takes orders from the pituitary gland, which responds to signals from the hypothalamus. The hypothalamus, sitting above the pituitary gland, has only one job: maintaining homeostasis. Part of maintaining stability in the body is managing hormones.
While a part of the brain, the hypothalamus is also a member of the hypothalamic-pituitary-thyroid (HPT) axis, a network critical to metabolic function. However, the hypothalamus is not the only controlling member in the network. The pituitary gland sometimes supersedes directions from the brain to help regulate hormones — a biological balance of power.
Typically, the hypothalamus signals the pituitary gland by producing and sending thyrotropin-releasing hormone (TRH), which encourages the pituitary gland to create and send thyroid-stimulating hormone (TSH) to the thyroid gland. Finally, the thyroid produces the necessary hormones. However, the pituitary gland can also send TSH to the thyroid without the hypothalamus if it senses an imbalance in the blood.
Despite the apparent checks and balances of the HPT, problems can occur. Over- or underproduction of T3 and T4 can happen, and the issue can lead to lifelong health conditions.
Understanding Hyper- and Hypothyroidism
A thyroid gland is usually a well-oiled machine, producing the exact amount of hormones necessary to maintain and balance the body's metabolism. Unfortunately, several disorders can affect the production of thyroid hormones, resulting in too much or too little in the blood.
A condition known as hyperthyroidism occurs when the thyroid gland consistently produces too much hormone. Someone with hyperthyroidism might experience several symptoms, including:
- Increased heart rate
- Weight loss
- Muscle weakness
- Eye irritations
- Sleep problems
Hypothyroidism occurs when the thyroid gland produces too little hormone, resulting in slower or faster energy usage. Someone with hypothyroidism might experience several symptoms, including:
- Slower heart rate
- Hoarse voice
- Dry skin and hair
Nearly 20 million people in the U.S. have a thyroid condition, making it relatively common. However, women are five to eight times more likely to receive a diagnosis than men.
The thyroid gland is vital to the body's equilibrium. While it is a small piece of the endocrine system, its role is crucial to hormone regulation and management. If you are experiencing any symptoms related to hyper- or hypothyroidism, schedule an appointment with your primary care physician.