Thyroid Disease 101

Basic Information on Hypothyroidism, Hyperthyroidism, Nodules, Goiter and Cancer

The thyroid is your master gland of metabolism, and energy.. istockphoto

The thyroid is a small gland, shaped like a butterfly, located in the lower part of the neck. The function of this gland is to secrete hormones. The main hormones released by the thyroid are triiodothyronine, abbreviated as T3, and thyroxine, abbreviated as T4. These thyroid hormones deliver energy to cells of the body.

What Diseases and Conditions Affect the Thyroid?

The most common problems that develop in the thyroid include:

  • Hypothyroidism -- An underactive thyroid.
  • Hyperthyroidism -- An overactive thyroid.
  • Goiter -- An enlarged thyroid.
  • Thyroid Nodules -- Lumps in the thyroid gland.
  • Thyroid Cancer -- Malignant thyroid nodules or tissue.
  • Thyroiditis -- Inflammation of the thyroid.
  • Autoimmune Hashimoto's Disease - an autoimmune disease that causes the thyroid to become underactive.
  • Autoimmune Graves' Disease - an autoimmune disease that causes the thyroid to become overactive. 

Signs and Symptoms


Thorough Diagnosis involves a clinical examination and blood tests.  In some cases, imaging tests and a biopsy are necessary.


When the thyroid gland is underactive, improperly formed at birth (known as congenital hypothyroidism), surgically removed all or in part, or becomes incapable of producing enough thyroid hormone, a person is said to be hypothyroid.

One of the most common causes of hypothyroidism is the autoimmune disease called Hashimoto's disease, in which antibodies gradually target the thyroid and destroy its ability to produce thyroid hormone.

In some parts of the world, the main cause of hypothyroidism is iodine deficiency

Symptoms of hypothyroidism usually go along with a slowdown in metabolism, and can include fatigue, weight gain, depression, infertility, hair loss, constipation, among others.


When the thyroid gland becomes overactive and produces too much thyroid hormone, a person is said to be hyperthyroid.

The most common cause of hyperthyroidism is the autoimmune condition known as Graves' disease, where antibodies target the gland and cause it to speed up hormone production.

Autoimmune Thyroid Disease

Most thyroid dysfunction such as hypothyroidism or hyperthyroidism is due to autoimmune thyroid disease.

Autoimmune disease refers to a condition where the body's natural ability to differentiate between its tissues, organs and glands, vs. outside bacteria, viruses or pathogens, becomes disrupted. This causes the immune system to wrongly mount an attack on the affected area, by producing antibodies.

In the case of autoimmune thyroid disease, antibodies either gradually destroy the thyroid, or make it overactive.

Goiter/Thyroid Nodules

Sometimes the thyroid becomes enlarged -- due to Hashimoto's disease, Graves' disease, nutritional deficiencies, or other thyroid imbalances. When the thyroid become enlarged, this is known as a goiter.

Some people develop solid or liquid filled cysts, lumps, bumps and tumors -- both benign and cancerous -- in the thyroid gland. These are known as thyroid nodules.

Thyroid Cancer

A small percentage of thyroid nodules are cancerous. While thyroid cancer is a rare cancer, it's on the rise. Learn more about thyroid cancer in these articles:


When the thyroid becomes inflamed, due to bacterial or viral illness, this is known as thyroiditis. There are a number of types of thyroiditis:

Thyroid Surgery

Surgery is usually performed for thyroid cancer, for some cases of goiter or nodule, and less commonly, as a hyperthyroidism treatment.

Thyroid Hormone Replacement Medications

Thyroid drugs are an important part of treatment for many patients.

Graves' Disease and Hyperthyroidism Treatment

Treatment of Graves' Disease and Hyperthyroidism reviews antithyroid drug treatment, radioactive iodine ablation, and surgery for an overactive thyroid

Still Don't Feel Well?

Some people don't feel well, even after treatment. If you fall into this category, you're probably frustrated, but there are solutions.

Doctors for Your Thyroid Treatments

It's important to find the right doctor for your thyroid care, and to work effectively with that practitioner.

Pregnancy, Fertility, Breastfeeding

Are you pregnant, trying to conceive, or breastfeeding? Thyroid disease poses particular challenges.

Weight Loss Challenges

Weight problems and difficulty losing weight are unfortunate side effects for many thyroid patients.

How to Stay Informed

  • Sign up for Mary Shomon's free weekly email Thyroid Newsletter at, which features the latest news on thyroid disease diagnosis, treatment, and related health issues of interest.
  • On Facebook: Join thyroid advocate, bestselling author, and Thyroid Expert Mary Shomon and her community of 75,000 thyroid patients for support, information, and the latest news and research, at: Thyroid Support on Facebook
  • On Twitter: Follow Mary Shomon on Twitter @ThyroidMary

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