What Are Thyroid Problems?

Through the hormones it produces, the thyroid gland influences almost all of the metabolic processes in your body. Thyroid disorders can range from a small, harmless goiter (enlarged gland) that needs no treatment to life-threatening cancer. The most common thyroid problems involve abnormal production of thyroid hormones. Too much of these vital body chemicals results in a condition known as hyperthyroidism. Insufficient hormone production leads to hypothyroidism.

Although the effects can be unpleasant or uncomfortable, most thyroid problems can be managed well if properly diagnosed and treated.

What Causes Them?

All types of hyperthyroidism are due to an overproduction of thyroid hormones, but the condition can occur in several ways: In Graves' disease, the release of excess hormones is triggered by an autoimmune disorder. For some unknown reason, the body attacks the thyroid, causing it to spill out too much hormone. At other times, nodules called toxic adenomas develop in the thyroid gland and begin to secrete thyroid hormones, upsetting the body's chemical balance; some goiters may contain several of these nodules. In subacute thyroiditis, inflammation of the thyroid causes the gland to "leak" excess hormones, resulting in temporary hyperthyroidism that generally lasts a few weeks but may persist for months. Although rare, hyperthyroidism can also develop from pituitary gland malfunctions or from cancerous growths in the thyroid gland.

Hypothyroidism, by contrast, stems from an underproduction of thyroid hormones. Since your body's energy production requires certain amounts of thyroid hormones, a drop in hormone production leads to lower energy levels. A common cause of hypothyroidism is Hashimoto's thyroiditis, an autoimmune disorder in which the body attacks thyroid tissue. The tissue eventually dies and stops producing hormones.

Hypothyroidism can also result when the thyroid gland has been surgically removed or chemically destroyed as treatment for hyperthyroidism. If you are exposed to excessive amounts of iodide -- perhaps from a hidden source such as cold and sinus medicines, the heart medicine amiodarone or from certain contrast dyes given before some x-rays -- you may be at greater risk for developing hypothyroidism, especially if you have had thyroid problems in the past. The drug lithium has also been linked as a cause of hypothyroidism. Untreated for long periods of time, hypothyroidism can bring on a myxedema coma, a rare but potentially fatal condition that requires immediate hormone injections.

Hypothyroidism poses a special danger to newborns and infants. A lack of thyroid hormones in the system at an early age can lead to the development of cretinism (mental retardation) and dwarfism (stunted growth). Most infants now have their thyroid levels checked routinely soon after birth. If they are hypothyroid, treatment begins immediately. In infants, as in adults, hypothyroidism can be due to a pituitary disorder, a defective thyroid, or lack of the gland entirely. A hypothyroid infant is unusually inactive and quiet, has a poor appetite and sleeps for excessively long periods of time.

Cancer of the thyroid gland is quite rare and occurs in less than 10% of thyroid nodules. You might have one or more thyroid nodules for several years before they are determined to be cancerous. People who have received radiation treatment to the head and neck earlier in life, possibly as a remedy for acne, tend to have a higher-than-normal propensity for thyroid cancer.