What Is the Thyroid?

The thyroid is a butterfly-shaped gland that regulates the body’s metabolism and organ function. The gland is located across the base of the neck below the Adam’s apple and in front of the windpipe.

The thyroid produces hormones that affect nearly every tissue in the body. Some of the functions the thyroid hormones are involved in include the breakdown of fat tissue, the pace of cell activity, menstrual cycling, heart rhythms, and protein building and breakdown. The thyroid also helps to maintain blood pressure and regulates tissue growth and development.

The thyroid gland produces the thyroid hormone levothyroxine (T4) which in turn is converted to another hormone tri-iodothyromine (T3) in other body tissues. These two thyroid hormones, T3 and T4, travel to all parts of the body where they influence metabolism.

One of the roles of the pituitary gland is to regulate the amount of thyroid hormones that are produced. As the pituitary monitors the thyroid hormone level in the blood, it produces its own hormone – thyroid stimulating hormone (TSH), which travels in the blood to the thyroid to stimulate the production of thyroid hormone.

What Are Thyroid Disorders?

Disorders of the thyroid can affect the cardiovascular system, reproductive system and major organs.

About 20 million Americans, mostly women, have a thyroid disorder of some form. The most common thyroid disorder is an under-active thyroid, or hypothyroidism, where the thyroid fails to produce enough hormones. Hyperthyroidism, or an over-active thyroid, occurs when too much thyroid hormone is produced. Sometimes there can be an overgrowth of tissue causing a small lump, or nodule, on the gland. Most nodules are benign, but a small percentage may be cancerous.

What Is Hypothyroidism?

Hypothyroidism is a disease wherein the thyroid fails to produce enough thyroid hormone (TH). When too little TH is released, the body’s metabolic rate decreases and the body slows down. With mild hypothyroidism, there may be no obvious symptoms, but as the thyroid failure progresses, symptoms may begin to emerge. Symptoms of hypothyroidism include:

  • Fatigue
  • Intolerance to cold
  • Depression
  • Dry, coarse skin and hair, hair loss
  • Brittle nails
  • A slow heart rate
  • Constipation
  • Trouble with concentration
  • Poor memory
  • Irregular or heavy menstruation
  • Infertility
  • Muscle aches
  • High cholesterol
  • Goiter (or enlarged thyroid gland)

What Causes Hypothyroidism?

The leading cause of a hypothyroidism is Hashimoto’s Thyroiditis, an autoimmune disease. When a person has Hashimoto?s Thyroiditis, that person’s immune system attacks and damages the thyroid gland as though it were a foreign substance. The final result is that decreased amounts of TH are produced.

As there is less TH circulating in the blood, the pituitary gland will produce more TSH, causing the thyroid gland to work harder. This increase in demand may cause the thyroid to grow larger, resulting in a goiter.

Another cause of hypothyroidism can be a hyperactive nodule that causes the rest of the thyroid to be under-active (see nodules below).

Hypothyroidism can occur after treatment for hyperthyroidism (see hyperthyroidism below), or it can occur spontaneously.

Another cause of hypothyroidism can be a hyperactive nodule that causes the rest of the thyroid to be under-active.

Hypothyroidism can also occur after treatment for hyperthyroidism, or it can occur spontaneously.

Hypothyroidism can occur during pregnancy or postpartum. Hypothyroidism can be difficult to diagnose during pregnancy since the symptoms of fatigue and weight gain can also be normal symptoms of pregnancy. Hypothyroidism can be safely treated during pregnancy with a thyroid supplement. Women who were already on a thyroid medication before pregnancy may need their dose adjusted during pregnancy.

How Is Hypothyroidism Treated?

The goal is to replace the missing thyroid hormone with a supplemental synthetic hormone. The supplemental hormone will probably have to be taken for life. Periodic TSH (thyroid stimulating hormone) tests are necessary to monitor the TH levels, as the body’s requirement may change over time. Patients should not change their brand of thyroid hormone without first consulting with their physician.

What Is Hyperthyroidism?

Hyperthyroidism occurs when too much thyroid hormone is released. When this occurs, metabolism increases and the body speeds up. Symptoms of hyperthyroidism include:

  • Tremors
  • Rapid pulse
  • Nervousness or irritability
  • Heat intolerance
  • Difficulty sleeping
  • More frequent bowel movements
  • Decreased menstrual flow
  • Weight loss
  • Bulging of the eyes (exothalmos)
  • Muscle weakness
  • Goiter (enlarged thyroid gland)

What Causes Hyperthyroidism?

The leading cause of hyperthyroidism is Grave’s Disease, an autoimmune disease. When a person has Grave?s Disease, the body’s immune system mistakenly attacks thyroid tissue, causing excessive growth of the tissue leading to an enlarged thyroid. This leads to an overproduction of thyroid hormone. The antibodies may also attack eye muscle and the skin.

A thyroid nodule that overproduces TH can also cause hyperthyroidism. It can develop during or after pregnancy, or after treatment for hypothyroidism with too high a dose of synthetic hormone.

How Is Hyperthyroidism Treated?

An anti-thyroid medication can be given to block the production of thyroid hormone in very young patients with Grave’s disease or elderly patients with diseased thyroid glands. Part or all of the thyroid gland may be surgically removed. Often radioactive iodine is given to shut down the thyroid hormone production. Patients then would take synthetic thyroid hormone.

What Is a Thyroid Nodule?

A nodule is a lump in the thyroid gland. Usually, your physician will check the nodule with an ultrasound or a biopsy to see if it is cancerous or benign. 90 to 95% of thyroid nodules are benign.

If the nodule is found to be benign, a thyroid hormone may be prescribed to shrink the size of the nodule or it may be removed surgically. If the nodule is found to be cancerous, further treatment will be necessary. Thyroid cancer can usually be successfully treated.

Most nodules don’t have symptoms and may never be detected. Some nodules grow large enough to press against the windpipe and cause difficulty with swallowing.