Epidemiology of Graves' orbitopathy (GO) and relationship with thyroid disease.

The incidence of Graves' orbitopathy (GO) is 16/100,000 in females and 2.9/100,000 in males as studied in Olmsted county. It can be calculated that the approximate prevalence is 0.25%. There is a gender bimodal distribution. Go usually occurs at the time of onset of the hyperthyroidism but may present up to a year before that time or as long as 5 years afterwards. Around 10-15% of patients have never been hyperthyroid and some are hypothyroid at GO presentation. Although the incidence of GO has probably been decreasing during the last 2 decades definite figures for this assertion are not available. Risk factors that may influence the incidence of GO include cigarette smoking and radioiodine treatment of hyperthyroidism. There are also complex genetic factors with multiple susceptibility alleles that contribute to the expression of the disease. The probability is that a reduction of the incidence of GO will be achieved by influencing the environmental factors.