Thyroid disease occurs when the thyroid gland, located at the front of the neck, produces either too many or too few hormones. Some common disorders of the thyroid include hyperthyroidism, hypothyroidism, thyroid nodules, thyroiditis, thyroid cancer and goiters.
Hyperthyroidism occurs when the thyroid gland is overactive and produces too many hormones. The most common cause of hyperthyroidism is Graves' disease, an autoimmune disorder which stimulates the thyroid to produce too many hormones.
Hypothyroidism occurs when the thyroid gland does not make enough hormones. Hypothyroidism may also cause high blood levels of LDL cholesterol, sometimes called the "bad" cholesterol. The most common cause of hypothyroidism in the United States is Hashimoto's disease.
Thyroid nodules cause swelling in one section of the thyroid gland. These nodules may be solid or filled with fluid or blood. Thyroiditis is inflammation, or swelling, of the thyroid which seems to be caused by a problem with the immune system. People with thyroid cancer usually have a thyroid nodule that is not causing any symptoms. If the cancer mass is large enough, it may cause swelling in the neck, pain or problems swallowing, or a hoarse voice. A goiter refers to an abnormally enlarged thyroid gland that causes swelling in the neck.