Symptoms of overactive thyroid, or hyperthyroidism, include double vision, bulging eyes, hair loss, heart arrhythmia, goiter, muscle weakness and rapid heartbeat, states WebMD. These symptoms are often unclear and can al... More »

High thyroid levels, or hyperthyroidism, is most commonly caused by Graves’ disease, but can also be caused by multinodular or toxic nodular goiters, excess consumption of iodine or medications that contain iodine, accor... More » Health Conditions & Diseases

High levels of thyroid indicate hyperthyroidism, a condition whereby the thyroid gland produces too much thyroid hormone, according to WebMD. The most common cause of this is Grave's disease, which tends to be hereditary... More »

Symptoms of overactive thyroid, or hyperthyroidism, include a fast or irregular heart rate; feeling nervous, moody, weak or tired; feeling very hot and sweating often; and having warm, red, itching skin, states WebMD. Ha... More » Health Conditions & Diseases

Possible causes of an overactive thyroid, or hyperthyroidism, include Graves' disease, thyroiditis, a thyroid nodule or too much iodine levels in the body, according to WebMD. Taking excessive thyroid hormone medications... More »

The most common side effect of high thyroid levels, or hyperthyroidism, is a protruding lump in the throat, which is also known as a goiter, according to WebMD. The heartbeat is sometimes irregular or very fast. Hair fal... More » Health Conditions & Diseases

An overactive thyroid produces more thyroid hormones than the body needs, and the medical term for the condition is hyperthyroidism, according to WebMD. Women have a higher risk of developing the condition than men. More » Health Conditions & Diseases