Graves disease is an autoimmune disease. The resulting hyperthyroidism and goiter causes exophthalmos and a peau d'orange induration of the skin that usually is localized over the tibia, which differentiates it from the more generalized, dry, doughy skin of hypothyroidism. An elevated erythrocyte sedimentation rate (ESR), painful thyroid enlargement, and thyrotoxicosis are diagnostic of subacute (DeQuervain's) thyroiditis. In this disease, a viral infection is thought to cause inflammation and abnormal release of thyroid hormone from the gland. Patients with multinodular goiter may develop thyrotoxicosis if excess iodine is ingested or injected, such as that contained in iodinated radiologic contrast media. In patients with goiter who require such contrast, pretreatment with thyroid blocking drugs such as propylthiouracil should be considered.