The signs and symptoms of Graves' disease generally result from the direct and indirect effects of hyperthyroidism (excessive thyroid hormone production); exceptions are caused by the autoimmune processes of Graves' disease, such as Graves' ophthalmopathy, goitre and pretibial myxedema. These clinical manifestations can involve virtually every system in the body. The mechanisms that mediate these effects are not well understood. The severity of the signs and symptoms of hyperthyroidism is related to the duration of the disease, the magnitude of the thyroid hormone excess, and the patient's age. Although the vast majority of patients enjoy significant improvement and remission after proper medical care, health care providers should be aware of variability in the individual response to hyper