The overall prevalence of hyperthyroidism is around 1.3 percent, it increases to 5 percent in older women. ^[1] 60-80% of the cases of thyrotoxicosis in the United States are caused by Graves’ disease. The incidence of Graves’ disease has been reported to be 50 cases per 100,000 people, with the peak occurrence in ages 20-40 years. Toxic multinodular goiters occur in patients with a long history of nontoxic goiter and therefore are usually present after 50 years of age. Patients with toxic adenomas present at a younger age than do patients with toxic multinodular goiter.

Hyperthyroidism is more common in women than men (5:1 ratio). Toxic nodular goiter is more common in older women, while Graves’ disease is seen most often in younger women. Graves ophthalmopathy is more common in women than in men.

Autoimmune thyroid disease occurs with the same frequency in Caucasians, Hispanics, and Asians but at lower rates in African Americans. Hyperthyroidism is also more common in smokers. ^[2]