The thyroid is a small gland, shaped like a butterfly, located in the lower part of your neck. The function of a 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

If you are wondering if you might have one of these thyroid conditions, take an interactive self-test online: Quiz: Could You Have a Thyroid Problem?.
And read Top Ten Signs You Have a Thyroid Problem.
Diagnosis

Thorough Diagnosis involves a clinical examination, blood tests, and in some cases, imaging tests and a biopsy.

The Clinical Thyroid Examination
Thyroid Blood Tests
Thyroid Imaging Tests – MRIs, Ultrasounds, X-Ray Uptake Scans
Fine Needle Aspiration Biopsy of the Thyroid
Hypothyroidism

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.

The Hypothyroidism Risks/Symptoms Checklist reviews the key symptoms.
Quiz: Could You Be Hypothyroid? is a self-test to help you identify risks and symptoms.
Hyperthyroidism

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.

Quiz: Could You Be Hyperthyroid? is an interactive self-test.
Overview of Graves’ Disease and Hyperthyroidism — features a thorough look at overactive thyroid problems
Risks and Symptoms assesses the various risk factors, triggers, signs and symptoms of an overactive thyroid
Diagnosis of Graves’ Disease and Hyperthyroidism evaluates the blood tests, imaging tests and clinical evaluation involved in diagnosis
Treatment of Graves’ Disease and Hyperthyroidism considers antithyroid drug treatment, radioactive iodine ablation, and surgery
Support / Coping with Graves’ Disease and Hyperthyroidism looks at various ways to live with these conditions
The 10 Things Your Doctor May Not Have Told You About Graves’ Disease has additional important information.
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.

To understand the difference between an underactive thyroid and Hashimoto’s disease, read: Hashimoto’s vs. Hypothyroidism: What’s the Difference?
In some cases, the autoimmune disease itself may warrant treatment, as described in Treatment Can Help Those Who Test Positive for Thyroid Antibodies
Having one autoimmune disease increases the personal and family risk of other autoimmune diseases. The Autoimmune Disease Checklist looks at various symptoms that are common to these types of diseases.
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.

Sometimes you can find a thyroid lump yourself by performing a Thyroid Neck Check
All About Thyroid Nodules, Lumps and Goiter helps you understand these problems, how they’re diagnosed and treated.
Biopsy is sometimes needed to rule out cancer in a nodule. Here’s a Q&A on Fine Needle Aspiration Biopsy.
If you get an indeterminate or inconclusive fine needle aspiration biopsy result, you’ll want to learn about the Veracyte Afirma Thyroid Analysis.
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:

Thyroid Cancer Facts, Statistics, and How to Do a Thyroid Neck Check
Thyroid Cancer Risk Factors
Thyroid Cancer Symptoms
Thyroid Cancer Diagnosis
Thyroiditis

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

Understanding Thyroiditis
Riedel’s Thyroiditis
Subacute Granulomatous Thyroiditis
Acute Infectious Thyroiditis
Painless Thyroiditis
Postpartum Thyroiditis
Thyroid Surgery

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

Before thyroid surgery, it is crucial to find a qualified thyroid surgeon.
Read Thyroid Surgery for a detailed overview of what to expect from thyroid surgery.
In some cases, there are Complications After Thyroid Surgery that you should know about.
Finally, after surgery, here are some tips on Recuperating After Thyroid Surgery.