Curious about the thyroid and its impact on your health? Discover how this small gland influences everything from metabolism to mood, learn the signs of common thyroid disorders, and find out what to watch for when it comes to thyroid cancer. Get the facts you need to keep your thyroid—and your body—healthy!
In this article:
- The thyroid is a hormone-producing gland at the base of the neck that regulates essential body functions such as metabolism, heart rate, and temperature; it requires iodine to produce its main hormones, T4 and T3.
- Thyroid disorders include hyperthyroidism (overactive thyroid, often caused by Graves’ disease) and hypothyroidism (underactive thyroid, commonly due to Hashimoto’s thyroiditis), each with distinct symptoms and treatment options.
- Thyroid cancer is relatively common, especially in women, and risk factors include age, gender, family history, and radiation exposure; treatment typically involves surgery and may include additional therapies.
The thyroid is a bow tie-shaped gland located at the base of the neck. It is part of the endocrine system, a network of glands that release hormones directly into the bloodstream. Hormones act as chemical messengers that regulate many of the body’s vital functions. Unlike exocrine glands, such as sweat or salivary glands, which release substances through ducts, endocrine glands — including the thyroid and pituitary — secrete hormones directly into the blood.
What is the thyroid’s function?
Thyroid hormones regulate many essential metabolic processes, including breathing, heart rate, body weight, muscle strength, body temperature, cholesterol levels, menstrual cycles and nervous system function. They are also critical to brain development in infants and children.
Is the thyroid the same as the Adam’s apple?
No, but this is a common misconception. The thyroid sits below the Adam’s apple, which is part of the larynx, a structure involved in breathing and vocalization. Both men and women have a larynx. However, during puberty in males, testosterone causes the Adam’s apple to grow larger and the vocal cords to thicken. This results in a deeper voice and a more prominent Adam’s apple.
What hormones does the thyroid make?
The thyroid is regulated by the pituitary gland in the brain, which produces thyroid-stimulating hormone, or TSH. The pituitary signals the thyroid to produce the following hormones as needed:
- Thyroxine (T4): The primary hormone produced by the thyroid. T4 is considered a prohormone because it is converted into the more potent hormone T3.
- Triiodothyronine (T3): Produced by the thyroid in much smaller amounts than T4 but significantly more potent. About 20 percent of the T3 in the body is produced by the thyroid; the remainder results from the metabolic conversion of T4 to T3, primarily in the liver and kidneys.
- Calcitonin: Helps regulate calcium levels in the blood by decreasing them as needed.
What is the connection between the thyroid and iodine?
The thyroid uses iodine from food to produce T4 and T3. T4 contains four iodine atoms, while T3, the more active hormone, contains three. Iodine deficiency once commonly caused goiters. Today, iodized salt and foods such as dairy products, eggs and seafood generally provide adequate iodine. Supplements are unnecessary and may even be harmful.
What is hyperthyroidism?
Hyperthyroidism occurs when the thyroid produces too much thyroxine. Causes include thyroid nodules, inflammation, excess iodine in the diet and an autoimmune disorder called Graves’ disease. Untreated, hyperthyroidism can lead to heart rhythm problems, blood clots, osteoporosis, fertility issues, pregnancy complications, stroke and heart failure. Treatment may include antithyroid medications, radioactive iodine or surgery.
What are the symptoms of hyperthyroidism?
Hyperthyroidism can be difficult to diagnose as it can cause a wide range of symptoms, including:
- Unexplained weight loss
- Fast or irregular heartbeat and palpitations
- Increased appetite
- Anxiety and irritability
- Tremor in the hands and fingers
- Sweating
- Changes in menstrual cycles
- Increased sensitivity to heat
- More frequent bowel movements
- Enlarged thyroid gland, or goiter
- Fatigue
- Muscle weakness
- Sleep problems
- Warm, moist or thinning skin
- Fine, brittle hair
What is Graves’ disease?
Graves’ disease is an autoimmune condition that causes hyperthyroidism. Symptoms are similar, but an additional complication called thyroid eye disease, or Graves’ ophthalmopathy, may occur. This chronic inflammation and swelling of tissue around the eyes can cause the eyes to bulge over time.
What is hypothyroidism?
Hypothyroidism occurs when the thyroid produces too little thyroxine. The most common cause is an autoimmune disorder called Hashimoto’s thyroiditis. It can also result from medication or radiation therapy. Untreated, hypothyroidism can lead to goiter, depression, high cholesterol, nerve damage and, in severe cases, a potentially fatal condition called myxedema. Fortunately, hypothyroidism can be treated — and often prevented — with regular doses of synthetic thyroid hormone.
What are the symptoms of hypothyroidism?
Symptoms may include:
- Fatigue
- Unexplained weight gain and difficulty losing weight
- Sensitivity to cold
- Constipation
- Dry skin
- Hair loss
- Muscle and joint pain
- Depression and mood changes
- Impaired memory and concentration
- Irregular menstrual periods
- Hoarseness
- Thyroid nodules, or lumps
What is Hashimoto’s disease?
Hashimoto’s disease, also called Hashimoto’s thyroiditis, is a progressive autoimmune condition that destroys thyroid hormone-producing cells. The result is hypothyroidism, with symptoms like those listed above.
How common is thyroid cancer?
Thyroid cancer is the 12th most common cancer in the United States. The American Cancer Society estimates that about 45,240 new cases — including 13,240 in men and 32,000 in women — will be diagnosed in 2026.
What are the risk factors for thyroid cancer?
- Gender: Women are three times more likely than men to develop thyroid cancer
- Age: Most cases occur in people ages 25 to 65
- Race: Thyroid cancer can occur in people of all races, but white and Asian individuals have a higher risk than Black individuals
- Goiter: A current or history of goiter
- Family history: Relative(s) diagnosed with thyroid disease or thyroid cancer
- Genetics: Certain rare thyroid cancers, including medullary thyroid cancer, have a genetic component
- Radiation exposure: Prior radiation therapy, radioactive iodine or other sources; routine dental X-rays, chest X-rays and mammograms are not associated with increased risk
- Low iodine diet
- History of breast cancer: Research is inconclusive, but some studies suggest breast cancer survivors may have a higher risk of thyroid cancer, and vice versa
What are the symptoms of thyroid cancer?
Thyroid cancer does not always cause symptoms, but when it does, they may include:
- A lump or swelling on the front or side of the neck
- Neck pain, sometimes radiating to the ears or jaw
- Difficulty breathing
- Difficulty swallowing
- Persistent hoarseness or other voice changes
- A constant cough
- A tickling sensation in the throat
- Sore throat
- Pain in the neck, jaw or ear
Thyroid cancer may also affect hormone production, causing symptoms such as flushing or diarrhea.
How is thyroid cancer treated?
Surgery is the primary treatment for most thyroid cancers, as well as for some benign thyroid nodules. Surgery may involve removing part of the thyroid, called a lobectomy, or the entire gland, known as a thyroidectomy. Depending on the cancer type, additional treatment may include radioactive iodine therapy, thyroid hormone therapy, external beam radiation, chemotherapy or targeted drug therapy.
Thyroid tests are often part of routine blood tests done during your annual physical. But if you experience any unusual symptoms or have concerns about your thyroid function, talk to your doctor. Find a doctor here.
This article first appeared in the February 2026 edition of the HealthPerks newsletter.
