Approximately 20 million Americans currently suffer from thyroid disease. This common but subtle illness can have an immense impact on a person's health and lifestyle. I chose to research thyroid disease because I did blood tests speculating about this disease due to the similar symptoms I was experiencing. Although I do not suffer from thyroid disease, I am curious about how it affects the body and why this condition often goes undiagnosed. This system involving the thyroid is crucial for regulating and maintaining the body's hormones. The thyroid is a butterfly-shaped gland located anteriorly in the lower neck. It is an endocrine gland composed of two vertically elongated lobes connected by the isthmus. Each lobe is between twelve and fifteen millimeters long. The thyroid is covered by a thin fibrous sheath and is surrounded by cartilage and neck muscles like the sternomastoid muscle. Above the collarbone, the thyroid is located next to the larynx and trachea. When swallowing, the thyroid moves because it is rigidly attached to the trachea. On the posterior side of each lobe are two parathyroid glands, responsible for helping to regulate calcium. The weight of the thyroid can vary from twenty to fifty grams in adults. Typically, women have a slightly heavier thyroid and this enlarges during menstruation and pregnancy. Within both lobes, the thyroid is made up of thyroid tissue containing many smaller lobules connected to connective tissues. Each lobule contains a large number of follicles that store thyroid hormone droplets. The thyroid is a crucial part of the endocrine system responsible for the growth and development of the body. It controls the pace of the body's activities and determines how fast the heart beats and how quickly calories are burned. Three