What is Graves Disease? And what is Hyperthyroidism? Such big words that only doctors and people who take the time will understand. I will try to get as much information as possible to explain these two terms. What are they? and what are the relationship? What is Graves Disease? Graves' Disease is a type of autoimmune disease that causes over-activity of the thyroid gland. What is autoimmune disease? Autoimmune disease is when the body's immune system become misdirected and attacks the organs/cells/tissues that it is supposed to protect. What is thyroid gland? The thyroid gland is one of the endocrine glands, which make hormones to regulate physiological functions in the body. The thyroid gland manufactures thyroid hormone, which regulates the rate at which the body carries on its necessary functions. Other endocrine glands are the pancreas, the pituitary, the adrenal glandsm the testes and the ovaries. The thyroid gland is located on the middle of the lower neck, below the larynx (voice box) and just above the clavicles (collarbones). It is shaped like a "bow tie". having 2 halves (lobes): a right lobe and a left lobe joined by an "isthmus". A normal thyroid gland usually cannot be felt. What is an Abnormal Thyroid Gland? Diseases of thyroid glands are very common. The most common diseases are an OVER- or UNDER-active gland. These conditions are called hyperthyroidism and hypothyroidism. Both these over and under activities can enlarge the thyroid gland. An enlarged thyroid gland is often called a "goiter". So now, having all the above definitions, we know that hyperthyroidism is just the condition where the thyroid gland is extremely active. And Graves' Disease is a disease that causes that condition.