The term "thyroid nodule" refers to any abnormal growth that forms a lump in the thyroid gland. The thyroid gland is located low in the front of the neck, below the Adam's apple. The gland is shaped like a butterfly and wraps around the windpipe or trachea. The two wings or lobes on either side of the windpipe are joined together by a bridge, called the isthmus, which crosses over the front of the windpipe.

A thyroid "nodule" is a localized swelling within the thyroid gland. Of most concern is a single swelling, but sometimes it is part of a "multinodular goitre" in which several such swellings are present. Multinodular goitre is not uncommon in older people and often causes no symptoms. Single nodules are also common, affecting perhaps 5% of the population - although most of those affected are not aware that there is anything wrong with their thyroid gland. There are many causes of single nodules in the thyroid gland.

The exact cause of thyroid nodules is unknown. But, they do know that people who have been exposed to radiation have a greater chance of developing thyroid nodules. Exposure to environmental radiation or past radiation treatment to the head, neck, and chest (mostly during childhood) increases your risk for thyroid nodules.Thyroid nodules can be genetic and do run in families. This means you are more likely to have a thyroid nodule if one of your parents has had a thyroid nodule.If you have another thyroid condition (such as goiter), you may also have a larger chance of developing thyroid nodules.

Symptoms of a nodule can be varied. Some people have hyperthyroidism symptoms -- such as palpitations, insomnia, weight loss, anxiety, and tremors -- and others have hypothyroidism symptoms -- weight gain, fatigue, depression. Some will cycle back and forth between hyperthyroid and hypothyroid symptoms. Some people mainly have difficulty swallowing, a feeling of fullness, pain or pressure in the neck, a hoarse voice, or neck tenderness. And finally, many people have nodules wiht no obvious symptoms related to thyroid dysfunction at all.

Thyroid nodules may be single or multiple. A thyroid gland that contains multiple nodules is referred to as a multinodular goiter. If the nodule is filled with fluid or blood, it is called a thyroid cyst. If the nodule produces thyroid hormone in an uncontrolled manner without regard to the body's needs, the nodule is referred to as autonomous. This type of nodule may cause signs and symptoms of too much thyroid hormone or hyperthyroidism, as mentioned above. Occasionally, patients with a thyroid nodule may have too little thyroid hormone or hypothyroidism.

If your thyroid nodule is causing hyperthyroidism, your doctor may recommend a dose of radioactive iodine, which usually comes in a liquid that you swallow. Your doctor may have you take medicine (antithyroid pills) for a few weeks to slow down the hormone production. Your thyroid hormone level needs to be normal before you can be treated with radioactive iodine.