What Is Thyroid Disease?

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Your thyroid gland can be affected by a number of specific diseases. Thyroid conditions such as hyperthyroidism or hypothyroidism typically result from underlying thyroid disease. It's estimated that about 20 million people in the United States have thyroid disease, making it one of the most common conditions.

Women make up the majority of thyroid patients. And unfortunately, people who have a thyroid problem but are not yet diagnosed make up the majority of thyroid patients.

Let's explore key information about various important aspects of thyroid disease.

Types of Thyroid Disease
Verywell / Emily Roberts


Your thyroid is a small, butterfly-shaped gland located in your neck—below and behind your Adam's apple—made up of four separate lobes. A healthy thyroid typically weighs about one ounce. The thyroid's function is to produce thyroid hormone, which is essential for all your body's functions.

Your thyroid gland is the main organ in the body that can absorb iodine. The thyroid takes iodine from your diet and converts it into thyroid hormones. It combines the amino acid tyrosine and iodine to make the thyroid hormone.

The two key hormones produced by the thyroid are thyroxine—known as T4—and triiodothyronine—known as T3, whose key purpose is to regulate how your cells, organs, tissues, and glands use oxygen and energy.

Everything in your body relies on thyroid hormone—including digestion, the growth of your hair and nails, your sex drive, and the function of your organs and glands. Your brain, heart, and metabolism are especially dependent on the right levels of thyroid hormone to function properly and well.

The thyroid operates in a feedback loop with your pituitary gland. The pituitary detects the levels of thyroid hormone circulating in your bloodstream and releases—or slows the release of—a hormone called Thyroid Stimulating Hormone (TSH). When TSH is released, its job is to stimulate the thyroid to produce more hormone. When TSH levels drop, the message to the thyroid is to slow down production of thyroid hormone.

Types of Thyroid Diseases

Hashimoto's Disease

Hashimoto's is an autoimmune disease, meaning that your immune system inappropriately attacks your own thyroid gland. The weapon? Thyroid-attacking antibodies that your body produces, including thyroid peroxidase antibodies (TPO) and thyroglobulin antibodies (TgAb).

Hashimoto's disease typically causes inflammation and the gradual destruction of your thyroid gland over time.

Most people with Hashimoto's end up with hypothyroidism, a condition of insufficient thyroid hormone.

Hashimoto's can, however, cause periods or phases of overactivity, known as hyperthyroidism. It also comes with an increased risk of thyroid nodules, goiter (an enlarged thyroid), and a slightly increased risk of thyroid cancer.

Graves' Disease

This disease is an autoimmune disease where your immune system inappropriately produces antibodies, known as thyroid stimulating antibodies (TSI). These antibodies overstimulate your thyroid gland and cause it to overproduce thyroid hormone.

In some cases, TPO and TgAb antibodies may also be elevated. The overstimulation of the thyroid results in an excess of thyroid hormone (hyperthyroidism) or thyrotoxicosis. Graves' disease is frequently accompanied by goiter and in some cases thyroid nodules.

Thyroid Cancer

This refers to cancer that develops in the thyroid gland. Thyroid cancer is most often found in nodules (fluid-filled or solid lumps) in the thyroid gland. Depending on the cancer's stage, it may spread to surrounding tissue.

Stages of thyroid cancer.

There are four types of thyroid cancer:

  1. Papillary or mixed papillary-follicular thyroid cancer which makes up about 80 percent of all thyroid cancers.
  2. Follicular thyroid cancer which makes up about 14 percent of cases (Hurthle cell cancer is a variant of follicular thyroid cancer and treated similarly).
  3. Medullary thyroid cancer which makes up about three percent of thyroid cancers.
  4. Anaplastic thyroid cancer which makes up about two percent of cases.

The majority of thyroid cancers are considered treatable and very survivable.


This is a category of thyroid diseases that involves inflammation of your thyroid gland. Thyroiditis can be caused by antibody attacks on your gland, viruses, and bacteria. The types of thyroiditis include:

  • Hashimoto's disease
  • Subacute granulomatous thyroiditis
  • Postpartum thyroiditis
  • Subacute lymphocytic thyroiditis
  • Drug-induced thyroiditis 

Treatment depends on the type of thyroiditis and ranges from monitoring and non-steroidal anti-inflammatory medications to antibiotics and thyroid hormone replacement medication.

Toxic Multinodular Goiter

This is a disease where the thyroid gland develops multiple nodules and enlarges (goiter). Frequently, the nodules are "functional," meaning that apart from the thyroid gland's hormone production, the nodules themselves also produce and release thyroid hormone. Toxic multinodular goiter frequently causes hyperthyroidism.

Resulting Thyroid Conditions


The most common thyroid condition is hypothyroidism, which refers to a condition where you do not have enough thyroid hormone. It has a number of causes:

  • Hashimoto's thyroiditis—an autoimmune condition that causes impairment or destruction of the thyroid gland.
  • Post-surgical hypothyroidism—after all or part of the thyroid gland has been surgically removed.
  • Post-ablation hypothyroidism—results after radioactive iodine treatment (RAI) used for thyroid cancer, Graves' disease, and in some cases of hypothyroidism and nodules.
  • Congenital hypothyroidism—when a baby is born without a thyroid gland or with a malformed gland that is not capable of producing enough thyroid hormone.
  • Iodine-deficiency hypothyroidism—due to a deficiency of iodine in the diet.
  • Drug- and supplement-induced hypothyroidism—prescription medications and supplements that have the ability to cause hypothyroidism.
  • Goitrogen-induced hypothyroidism—very high consumption of raw goitrogens—foods that have chemicals in them that slow the thyroid.
  • Secondary/central hypothyroidism—due to a defect in the functioning/communications of the pituitary gland and the hypothalamus.
  • Traumatic hypothyroidism—serious trauma to the neck, such as whiplash or breaking the neck, has been linked to the onset of hypothyroidism.
  • Hypothyroidism of unknown origin/idiopathic hypothyroidism—there are cases where the thyroid becomes underactive and no other underlying causes or diseases have been identified.


Hyperthyroidism refers to a condition where the thyroid gland is overproducing thyroid hormone. It also has a number of causes:

  • Autoimmune Graves' disease—the most common cause of hyperthyroidism.
  • Autoimmune Hashimoto's disease—sometimes causes periods of temporary hyperthyroidism.
  • Iodine-excess hyperthyroidism—results from overexposure or overconsumption of iodine.
  • Drug- and supplement-induced hyperthyroidism—results from several prescription drugs as well as certain over-the-counter supplements.
  • Toxic multinodular disease—a condition that frequently causes overproduction of thyroid hormone.
  • Thyroiditis—certain forms can cause periods of hyperthyroidism.
  • Pituitary-induced hyperthyroidism—where the thyroid gland can become overstimulated by the pituitary gland and produce excessive amounts of thyroid hormone.
  • Thyroid nodules—in some cases they can trigger overactivity of the surrounding thyroid gland, causing hyperthyroidism. They can also, on their own, produce thyroid hormone.


This refers to a condition where the thyroid gland is enlarged in size. Goiter can result from autoimmune Hashimoto's and Graves' diseases, iodine excess and deficiency, and nodular thyroid disease.

Thyroid Disease Symptoms

The symptoms of thyroid disease tend to reflect the gland's underactivity (hypothyroidism), overactivity (hyperthyroidism), autoimmune activation, and/or inflammation/enlargement/tenderness in the neck area (thyroiditis, nodules, cancer.)

Common symptoms of hypothyroidism include:

  • Fatigue
  • Weight gain
  • Inability to lose weight with diet and exercise
  • Constipation
  • Infertility
  • Changes in the menstrual cycle
  • Feeling cold
  • Hair loss (including the outer edge of the eyebrows)
  • Brain fog
  • Muscle and joint pains/aches

Common symptoms of hyperthyroidism include:

  • Anxiety
  • Insomnia
  • Panicky feeling
  • Tremors
  • Exaggerated reflexes
  • Elevated heart rate
  • Increase in the frequency of bowel movements
  • Feeling overheated
  • Unexplained weight loss

Symptoms in the neck and thyroid area that can suggest a thyroid problem include:

  • Neck discomfort
  • Visible thyroid enlargement or lump
  • Discomfort with ties, scarves, turtlenecks, or necklaces
  • Hoarseness
  • Sore throat
  • Soreness in neck
  • Difficulty swallowing
  • A feeling of something getting stuck in the throat

In some cases, thyroid diseases and conditions can have no symptoms at all, such as thyroid cancer or certain types of thyroiditis.


The key risk factors for thyroid disease include:

  • Iodine deficiency or excess
  • Exposure to radioactivity or radioactive fallout
  • Surgery or trauma to the neck area
  • Pregnancy or recent childbirth
  • Female gender
  • Personal or family history of autoimmune disease
  • Cigarette smoking


Diagnosis of a thyroid condition involves several key steps:

  • A clinical examination
  • Blood testing: Typically, blood tests include the thyroid stimulating hormone (TSH) test, free thyroxine (Free T4) and free triiodothyronine (Free T3) antibodies testing to diagnose Hashimoto's and Graves' disease.
  • Imaging tests: A variety of imaging tests are done to further evaluate the size, shape, and function of the thyroid gland. These tests also look at nodules or lumps and evaluate whether or not they are suspicious for thyroid cancer and require further evaluation. These tests include the radioactive iodine uptake (RAI-U), CT scans, magnetic resonance imaging (MRI), and ultrasound.
  • Fine needle aspiration biopsy: Fine needle aspiration (FNA) biopsy is done when thyroid nodules are considered suspicious and need to be tested for possible thyroid cancer.



This condition is treated with thyroid hormone replacement drugs. These are prescription medications that replace the missing thyroid hormone in the body.

  • The most commonly prescribed thyroid hormone replacement drug is known generically as levothyroxine, a synthetic form of the thyroid hormone thyroxine.
  • There is also a synthetic form of the T3 hormone, known as liothyronine, that is sometimes added to levothyroxine for T4/T3 combination treatment.
  • Also, there is a hormone replacement drug called natural desiccated thyroid, sometimes abbreviated NDT or called "thyroid extract." While it has been available for more than a century and is still in use today, NDT is considered controversial by the mainstream medical community.

Graves' Disease and Hyperthyroidism

There are three key ways that Graves' disease and chronic hyperthyroidism are treated:

  1. Antithyroid drug treatmentAntithyroid drugs, including methimazole (tapazole), carbimazole (neo-mercazole), and propylthiouracil (PTU), can slow down the thyroid's production of thyroid hormone.
  2. Radioactive iodine treatment (RAI)—Given in a single dose, either in a capsule or drink, it enters the thyroid, radiates thyroid cells, and damages and kills them. This shrinks the thyroid, slows down its function, and reverses hyperthyroidism.
  3. Thyroid surgery/thyroidectomy—In some cases, surgery is performed as a treatment for Graves' disease and hyperthyroidism, especially for people who cannot tolerate antithyroid drugs or are pregnant and RAI is not an option.

Thyroid Cancer

For more aggressive types of thyroid cancer, surgery may be followed by RAI treatment to ensure that all thyroid cells are destroyed, a process known as remnant ablation.

Treatment for thyroid cancer almost always involves surgical removal of the thyroid gland.

Following surgical removal of the thyroid gland, patients are functionally hypothyroid and require lifelong thyroid hormone replacement treatment. Less commonly, other treatments—including external beam radiation, chemotherapy, radiofrequency ablation, and percutaneous ethanol injections—are used.

Autoimmunity and Hashimoto's

Integrative and functional medicine practitioners sometimes treat autoimmune thyroid disease, especially Hashimoto's, with the drug low dose naltrexone (LDN) which may help lower antibodies.

Other treatment approaches include:

  • Supplementation with selenium to lower antibodies
  • Addressing related adrenal imbalances that may be complicating thyroid treatment
  • Dietary changes to reduce inflammation
  • Eliminating gluten from the diet due to a connection between gluten and autoimmunity
  • Stress reduction and management

Working With Your Healthcare Team

Surprisingly, one of the challenges in your thyroid diagnosis, treatment, and relief of symptoms may actually be your healthcare practitioners. The right doctor can make all the difference. To that end, it's important to know how to carefully choose the right kind of doctor for your thyroid care and to learn how to effectively communicate with them.

Thyroid Disease Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman

One question you may be wondering is whether or not you need an endocrinologist. The answer depends on your condition and your goals. If you do need an endocrinologist, you will want to make sure you find an endocrinologist with the right experience and qualifications. Also, you want to make sure that your doctor is providing the best possible care for your thyroid condition.

Living Well

Thyroid disease can affect many areas of life and you may need to cope with specific challenges.

Fertility and Pregnancy

The reproductive process is an especially important time to pay attention to thyroid health and function. Healthy thyroid function is required for fertility, a successful pregnancy, and postpartum health.

When there is an undiagnosed—or poorly treated—thyroid condition, it can have a number of effects, including:

  • Impaired fertility
  • Failed assisted reproduction treatments (such as in vitro fertilization)
  • Increased risk of early miscarriage
  • Increased risk of preeclampsia and prematurity
  • Increased risk of stillbirth
  • Increased risk of postpartum depression
  • Increased risk of breastfeeding problems

A good starting point is exploring the official guidelines for managing thyroid disease during and after pregnancy.

Diet, Weight Loss, and Fitness

One of the ways that some people discover they have a thyroid problem is the rapid onset of weight gain or a total inability to lose weight. For diagnosed and treated thyroid patients, one of the most common challenges is difficulty losing weight or weight gain, despite having a healthy diet and exercise program.

The link between thyroid function and metabolism is clear. Yet, mainstream medicine still downplays the relationship between hypothyroidism and weight gain, the difficulties people with hypothyroidism have losing weight, and the impact that thyroid issues have on gut health, digestion, blood sugar, and a healthy metabolism.

Most thyroid patients with weight struggles find it helpful to understand the factors that affect weight loss with hypothyroidism. This includes the roles of reverse T3 and leptin, two key hormones that affect thyroid patients' ability to lose weight.

A Word From Verywell

Anytime you are diagnosed with a chronic health problem, it can be confusing and frightening. Your best chance at health success involves becoming involved in and an advocate for your own thyroid care. And one of the key elements of being a successful thyroid patient is staying informed. That means reading, following the latest research, and connecting with others who can share their successful advice.

Learn as much as you can and make sure you manage stress—meditation, for example, may help alongside your medical thyroid treatment. Millions of people are living well with thyroid conditions and you too can be one of those success stories.

Read how thyroid disease causes dry mouth.

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Article Sources
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