source: National Organization for Rare Disorders summary/abstract:
Graves’ disease is a disease affecting the thyroid and often the skin and eyes. The thyroid is a gland and is part of the endocrine system, the network of glands that secrete hormones that regulate the chemical processes (metabolism) that influence the body’s activities as well as regulating the heart rate, body temperature, and blood pressure.
Hormones are secreted directly into the bloodstream where they travel to various areas of the body. Graves’ disease is characterized by abnormal enlargement of the thyroid (goiter) and increased secretion of thyroid hormone (hyperthyroidism).
Thyroid hormones are involved with many different systems of the body and, consequently, the specific symptoms and signs of Graves’ disease can vary widely from one person to another. Common symptoms include unintended weight loss, an abnormal intolerance of heat, muscle weakness, fatigue and protrusion or bulging of the eyeballs from their sockets.