What Is A Thyroid? Causes, Symptoms & Treatment

The thyroid produces hormones essential to the proper function of many bodily systems. Hyperthyroidism occurs when the thyroid creates too many hormones, while an underproduction causes hypothyroidism.

What Is The Thyroid Gland?

The thyroid gland is butterfly-shaped and located in the front of the neck. It wraps around the windpipe (trachea) and produces hormones that control how quickly your body uses energy, creates proteins, and handles how sensitive your body is to other hormones

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The thyroid gland is butterfly-shaped in the neck, releasing hormones that control metabolism. It consists of two lobes connected by a narrow bridge, each containing many follicles of a fibrous capsule surrounding a small core. The projections on the surface of the thyroid are called follicular cells; they produce and store thyroglobulin, which leaves the cells and enters blood vessels to be carried to various parts of the body.

What Does A Thyroid Gland Do?

The thyroid gland, located in the neck, secretes hormones that regulate the rate of chemical reactions in cells. These hormones are used by cells to produce heat and energy, as well as control protein production and break down certain substances in food. They also control how sensitive the body is to other hormones.

The thyroid gland produces thyroxine (T4) and triiodothyronine (T3), synthetic versions of iodine-containing substances called thyroid hormones. These two hormones work together to regulate metabolism or the rate at which your body uses energy.

Types Of Thyroid Disorders

Thyroid disorders affect the thyroid gland. There are many different types of thyroid disease, including Hashimoto's thyroiditis and Graves' disease.

• Hyperthyroidism
• Hypothyroidism
• Thyroiditis
• Hashimoto's thyroiditis
• Goiter 
• Thyroid nodules
• Thyroid cancer

1. Hypothyroidism

The thyroid gland normally produces a hormone called thyroxine (or T4). Hypothyroidism is when the thyroid does not produce enough of this hormone. As a result, many of the body's functions slow down. Scientists estimate that 1.8 million people in the US have hypothyroidism.

A decrease in the production of hormones characterizes hypopituitarism. It can cause symptoms like fatigue, breathing difficulties, and weight gain.

2. Hyperthyroidism

Hyperthyroidism is the most common form of thyroid disease, affecting about 2.6 million people in the United States. A condition characterized by an overproduction of thyroid hormones, hyperthyroidism can be treated with medication.

Hyperthyroidism is a disorder caused by an overactive thyroid gland, which results in excess thyroxine (a hormone produced by the thyroid) and can cause a wide range of symptoms, including anxiety, increased heart rate, and weight loss.

3. Thyroiditis And Hashimoto's Thyroiditis

Hashimoto's thyroiditis is the most typical cause of hypothyroidism in the US, affecting three to five million people. It is an autoimmune disease in which your body's immune system attacks your thyroid gland, resulting in inflammation that can disrupt its function. Hashimoto's can also cause symptoms like weight gain and fatigue.

4. Goiter

Goiter, or enlarged thyroid, is characterized by an abnormal lump in the neck that occurs when there is tissue swelling in front of the trachea and a lack of tissue behind the trachea containing lymph nodes.

5. Thyroid Nodules

Thyroid nodules are nonmalignant growths on the thyroid gland. They can be painless or cause symptoms such as pain and pressure in the neck, difficulty swallowing, hoarseness, and shortness of breath.

Nodules are not cancerous but can interfere with thyroid function, causing symptoms such as weight gain and fatigue. If you have a nodule causing these symptoms, see your doctor for evaluation.

6. Thyroid Cancer

Thyroid cancer is a type of cancer that develops in the thyroid gland. It is the most common form of endocrine cancer (a type of cancer that forms in hormone-producing cells) and accounts for about 1% of all cancers in the United States.

The thyroid gland is a small, butterfly-shaped organ near the base of the neck, which releases hormones that control many aspects of metabolism. When tissue in this gland becomes cancerous, it can overrun nearby tissues and spread to other parts of the body, where it might grow and form new tumors.

The most common treatment for thyroid cancer is the surgical removal of all or part of the thyroid gland, followed by radioactive iodine treatment or other forms of therapy.

Who Is Affected By Thyroid Disease

Researchers have identified several factors that contribute to the development of thyroid disease. Some people are born with an underactive or overactive thyroid gland genetically inherited; others develop hypothyroidism or hyperthyroidism due to an autoimmune disorder.

Other factors that can increase your risk of developing the disease include:

• Genetics
• Radiation
• Exposure to PCBs and other environmental chemicals
• Iodine deficiency (caused by inadequate intake of thyroid-supportive foods or a pro-iodide deficiency) can result in goiter.
• Autoimmune disease
• Family history

People who suffer from thyroid problems are often diagnosed with other health issues. For example, people with thyroid disease have a greater chance of developing diabetes.

People with thyroid problems are also more likely to develop mental health issues such as depression, anxiety, and bipolar disorder. It is possible that the thyroid hormone imbalance could cause these disorders or vice versa; further research is needed.

Causes Of Thyroid Diseases

The thyroid gland secretes two hormones: triiodothyronine (T3) and thyroxine (T4).

a. Causes Of Hypothyroidism

Hypothyroidism occurs when a person has insufficient T4 and T3 circulating in their bloodstream. Hashimoto's disease, an autoimmune condition that causes inflammation in the thyroid gland, is the primary cause of hypothyroidism.

• Hashimoto's Thyroiditis

Graves' disease is a manageable and painless disorder affecting the thyroid gland. It is an autoimmune condition in which the body's immune cells attack and damage the thyroid, causing it to enlarge. It is also known as Graves' hyperthyroidism because it causes thyroid overactivity. An inherited genetic defect on chromosome nine causes Graves' disease.

Other conditions that can cause hypothyroidism include:

• Thyroiditis

The thyroid gland in the neck produces hormones that regulate many functions, including body temperature, metabolism, and heart rate. Inflammation of the thyroid is called goiter. It can lead to hypothyroidism, a condition where the body produces too few hormones.

• Postpartum Thyroiditis

Postpartum depression affects 5% to 9% of women after childbirth. It is usually temporary, and women typically recover within six weeks.

• Iodine Deficiency

Iodine is an essential component of thyroid hormones. Several million people worldwide suffer from iodine deficiency, leading to various health problems.

• A Non-Functioning Thyroid Gland

The thyroid gland is one of the body's major endocrine glands, secreting hormones that regulate growth and metabolism. The thyroid gland may be nonfunctional at birth in about 1 out of every 4,000 newborns. Left untreated, congenital hypothyroidism can cause physical and mental disabilities later in life. All newborns are tested for this condition as part of standard medical practice.

In addition to the causes mentioned above, radiation exposure from nuclear disasters or accidents and the consumption of certain medications such as lithium, amiodarone, or interferon-alpha can also cause hypothyroidism.

b. Causes Of Hyperthyroidism

Hyperthyroidism is when the thyroid gland produces excessive amounts of thyroid hormone. Graves' disease is the most common cause of hyperthyroidism, an autoimmune disorder that occurs when the body's immune system attacks the thyroid gland.

• Graves' Disease

A goiter is an enlargement of the thyroid gland. In some people, the thyroid may overproduce hormones and cause the gland to enlarge greatly. This is called a diffuse toxic goiter.

Conditions such as Graves' disease and Hashimoto's thyroiditis can cause hyperthyroidism.

• Nodules 

Overactive nodules within the thyroid can cause hyperthyroidism. A single toxic nodule is a toxic autonomously functioning thyroid nodule, while a gland with several toxic nodules is called a toxic multi-nodular goiter.

• Thyroiditis 

Thyroiditis is an inflammation of the thyroid gland. It can be caused by various factors, including autoimmune disease and viral infections, but is most often linked to simple overuse of thyroid medication.

• Excessive Iodine

When someone has too much iodine in the body, the thyroid gland can receive an overabundance of thyroid hormone. This condition can be caused by taking medications such as amiodarone, a heart medication that contains iodine, drinking cough syrup, or having an iodine-based X-ray procedure.

In addition to the causes, as mentioned earlier, radioactive iodine for treating a previously-diagnosed thyroid nodule or goiter can also cause hyperthyroidism.

Symptoms Of Low & High Thyroid Levels

The symptoms of high and low thyroid levels can often be confused with one another because they share many similar symptoms. However, there are some distinguishing differences between the two conditions. Some symptoms are more common in one than the other.

Symptoms Of Low Thyroid (Hypothyroidism) Levels

• Weight gain
• Fatigue
• Hoarse voice
• Constipation
• Hair loss
• Dry hair
• Depression
• Forgetfulness
• Difficulty concentrating
• Intolerance to cold temperatures
• Heavy or frequent menstrual periods

Symptoms Of High Thyroid (Hyperthyroidism) Levels

• Weight loss
• Irritability
• Anxiety
• Difficulty sleeping
• Enlarged thyroid gland or a goiter
• Heart rate
• Irregular menstrual periods
• Menopause
• Muscle weakness
• Tremors
• Palpitations
• Vision problems
• Eye irritation
• Sweating
• Nervousness

Symptoms Of Thyroid Nodules

• Dysphagia (Narrowing of the esophagus which is caused by the tumor pressing on it)
• Difficulty swallowing
• Hoarseness
• Compression of vocal cords
• Compression on the part of the lung
• Shortness of breath

Symptoms Of Thyroid Cancer

• Swelling in the neck (below Adam's apple)
• Trouble swallowing
• Hoarseness or other voice changes
• Neck or throat pain
• Cough (lasting more than two weeks)
• Fever

Diagnosis For Thyroid Disease

The thyroid gland, located at the base of the neck, produces hormones that regulate metabolism and growth. Thyroid disease is one of the most common endocrine disorders in the United States and affects millions of people. There are different types of thyroid diseases, each with its own set of symptoms and treatment options. The diagnosis process includes the following:

• Physical exam
• Blood tests
• Imaging tests

i. Physical Exam

Thyroid disease can be determined through a physical examination. A goiter (enlargement of the thyroid gland in the neck) and nodules (small lumps on the thyroid gland) are two common indicators of thyroid disease. The healthcare provider will feel your neck for any growths or enlargements while performing this test.

ii. Blood Tests

Blood tests will measure the level of thyroid-stimulating hormone (TSH) in the blood and evaluate hormone levels, such as thyroxine (T4) and triiodothyronine (T3).

You can have the following thyroid tests done to check your thyroid levels:

• Thyroid-stimulating hormone (TSH)

The thyroid-stimulating hormone (TSH), a hormone produced in the pituitary gland that regulates the balance of thyroid hormones – including T4 and T3 – in the bloodstream, is typically the first test your provider will do to ensure your thyroid levels are balanced.

Doctors may measure the levels of thyroxine (T4) and triiodothyronine (T3) produced by the thyroid gland to determine if these hormones are functioning properly. Low levels of TSH can indicate that your thyroid gland is not producing enough hormones, while high levels may indicate an overactive thyroid gland.

• T4

Thyroxine blood tests diagnose and monitor thyroid gland disorders, with hypothyroidism indicated by low levels of thyroxine and hyperthyroidism indicated by high levels. The normal range is 5.0-11.0 ug/dL (micrograms per deciliter of blood).

• FT4

The free T4 test provides a more accurate measure of thyroid hormones because it eliminates the effect of proteins that bind T4 and makes accurate measurements difficult. The free T4 range for an adult should be 0.9-1,7 ng/dL.

• T3

Thyroid hormone tests, such as T3 tests, are often used to diagnose and manage people with hyperthyroidism. These tests can detect low T3 levels even in patients with hypothyroidism. The normal range is between 100 and 200 ng/dL (nanograms per deciliter of blood).

• FT3

The T3 resin uptake assay measures the amount of free T3 circulating in our body. Free T3 is a hormone produced in the thyroid gland. The slot-blot assay measures FT3 levels by collecting and running a blood sample through a specialized test strip. Normal ranges for FT3 are 2.30 – 4.10 pg/mL (picograms per milliliter of blood).

Additional blood tests might include:

• Thyroid Antibodies

Many physicians will administer a blood test to diagnose an autoimmune thyroid condition. Common thyroid antibody tests include TPO antibodies, TgAb (thyroglobulin antibodies), and thyroperoxidase antibodies.

• Microsomal antibodies (also known as thyroid peroxidase or TPO antibodies) are immunoglobulin used to identify autoimmune thyroid disease (AITD).
• Thyroglobulin antibodies (also known as TG antibodies) are proteins produced by the immune system to defend against thyroid gland tissue that has been damaged.
• Thyroid receptor antibodies (TRAbs) are proteins that circulate in the blood. TRAbs can signal thyroid cells to produce more hormones or block the production of hormones by interfering with receptor sites on thyroid cells.

• Calcitonin

This test is used to diagnose medullary thyroid cancer, a rare thyroid cancer in which the body produces too much thyroid hormone.

• Thyroglobulin

This test can be used to diagnose a patient with possible thyroiditis, or it can be administered to a patient diagnosed with thyroid cancer to monitor treatment progress.

iii. Imaging Tests

Thyroid scans, magnetic resonance imaging (MRI), or ultrasound imaging can be used to determine whether the thyroid gland is enlarged or contains nodules indicative of cancer.

• Thyroid Scan

A thyroid scan allows your physician to examine your thyroid, looking for signs of problems such as size and shape changes or the presence of nodules.

• Ultrasound

Ultrasound is a diagnostic technique to create visual images of internal organs and structures. Ultrasound uses high-frequency sound waves that are inaudible to the human ear but are detectable by the ultrasound machine's microphone. The echoes are recorded and transformed into video or photographic images. Unlike X-rays, ultrasounds do not use radiation.

Treatment For Thyroid Disease

Hyperthyroidism is a state in which the thyroid gland produces extreme amounts of the hormone thyroxine. Hypothyroidism, on the other hand, is a condition in which the thyroid gland produces insufficient amounts of thyroxine.

Treatment For Hyperthyroidism And Hypothyroidism

• Patients with hyperthyroidism are commonly treated with anti-thyroid drugs, such as methimazole and radioactive iodine therapy.
• Patients with hypothyroidism may be treated with medication to stimulate the thyroid gland and thyroid hormone replacement therapy.
• Thyroid surgery is a common treatment option for patients with hypothyroidism.

Treatment For Grave's Disease

• To help treat Grave's disease, patients may receive medications that reduce thyroid hormone production.
• Patients with Grave's disease may undergo thyroidectomy or thyroid lobectomy, which are surgeries to remove or reduce the size of the thyroid gland.
• Patients with Grave's disease may also be treated with radioactive iodine, administered as a pill or liquid.
• Patients with Grave's disease who are tested and found to be negative for thyroglobulin can receive thyroid hormone replacement therapy and medication to stimulate the thyroid gland.

Treatment For Radioactive Iodine Therapy

• Thyroid cancer patients usually receive treatments, including radioactive iodine and anti-thyroid drugs, surgery, and thyroid hormone replacement therapy.
• Radioactive iodine is used in a limited number of treatments for Grave's disease and is not used in all cases.
• For patients with Grave's disease who are negative for thyroglobulin, the radioactive iodine therapy treatment is recommended.
• Radioactive iodine therapy is contraindicated in patients with elevated levels of thyroglobulin.

Treatment for Thyroid Hormone Replacement Therapy

• Patients with Grave's disease who have insufficient thyroid hormone in their bodies may require thyroid hormone replacement therapy. Thyroid hormone replacement therapy may be prescribed for Grave's disease patients to control symptoms, but it does not prevent all of the manifestations of the disease. The therapy is delivered in the form of pills.
• Thyroid hormone replacement therapy is usually given in pill form, as an injection, or implanted under the skin.
• Radioactive iodine may be administered before or after thyroid hormone replacement for patients whose thyroid glands do not respond adequately to replacement hormone therapy.
• When treating hypothyroidism, doctors normally prescribe a small thyroid hormone for a few weeks and then gradually increase the dose until the patient's symptoms improve.

Conclusion & Takeaway

The thyroid gland is a small but important part of the endocrine system. It produces hormones that regulate metabolism, growth, and body temperature. Thyroid disease is a major health problem in the United States; more than 20 million people have been diagnosed with thyroid disease. If you are one of those people, take steps to avoid developing thyroid disease by following these guidelines:

• Do a self-exam once a month.
• Stay active and healthy.
• Get enough sleep at night.
• Only eat a little bread or cow's milk.
• Limit sodium intake
• Quit smoking

Hypothyroidism can harm many bodily systems, so it is not uncommon for people with thyroid disease to have other health problems. Monitoring your thyroid health can be an important preventative measure.

You can perform a self-exam. This will allow you to identify potential problems early on, which may help you avoid developing thyroid disease. A doctor can also check your thyroid function during an annual physical exam. If there are any concerns about your thyroid gland's health, they can diagnose any potential problems.

Thyroid Self-Exam

Examining the thyroid gland is usually done with a gloved hand—one finger placed on each side of the Adam's apple and then slid down until they meet at the bottom of the neck. The presence or absence of any lumps or bumps should be noted.