Thyroid Disorders

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.

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

About 20 million Americans have a thyroid disorder of some form, most of them women. The most common thyroid disorder is an under-active thyroid, or hypothyroidism, where the thyroid fails to produce enough hormone. 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.

How the Thyroid Works

The thyroid gland produces the thyroid hormone levothyroxine (T4) which in turn is converted to another hormone triiodothyromine (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.

Hypothyroidism

When too little thyroid hormone (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)

Causes

The leading cause of a hypoactive thyroid is Hashimoto's Thyroiditis, an autoimmune disease. A 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.

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.

Treatment

The goal is to replace the missing thyroid hormone with a synthetic hormone. The supplement 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 consulting with their healthcare provider first.

Hyperthyroidism

When too much thyroid hormone is released, 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)

The leading cause of hyperthyroidism is Grave's Disease. Grave's Disease is an autoimmune 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.

Treatment

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. Inderal may be prescribed for the tachycardia that can accompany hyperthyroidism.

Thyroid Nodule

A nodule is a lump in the thyroid gland. The nodule will probably be checked with ultrasound or a biopsy to see if it is cancerous or benign. Ninety to ninety-five percent of thyroid nodules are benign. Most nodules don't have symptoms and may never be deleted. Some nodules grow large enough to press against the windpipe and cause difficulty with swallowing.

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 CA can usually be successfully treated.

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