Autoimmune thyrotoxicosis: diagnostic challenges.

Autoimmune thyrotoxicosis or Graves' disease (GD) is the most common cause of hyperthyroidism in the United States (full text available online: http://education.amjmed.com/pp1/249). GD occurs more often in women (ratio 5:1) and has a population prevalence of 1-2%. A genetic determinant to the susceptibility to GD is suspected because of familial clustering of the disease, a high sibling recurrence risk, and the familial occurrence of thyroid autoantibodies. GD is a systemic autoimmune thyroid disorder characterized by the infiltration of immune effector cells and thyroid-antigen-specific T cells into the thyroid and thyroid stimulating hormone receptor (TSHR) expressing tissues, i.e. orbit, skin, with the production of autoantibodies to well-defined thyroidal antigens. Stimulatory autoantibodies in GD activate the TSHR leading to thyroid hyperplasia and unregulated thyroid hormone production and secretion. Diagnosis of GD is straightforward in a patient with a diffusely enlarged, heterogeneous, hypervascular (increased Doppler flow on neck ultrasound) thyroid gland, associated orbitopathy, biochemically confirmed thyrotoxicosis, positive TSHR autoantibodies, and often a family history of autoimmune disorders.