Incidence of hyperthyroidism in Stockholm, Sweden, 2003-2005

To investigate the incidence of hyperthyroidism in Stockholm County, in those patients who were diagnosed with hyperthyroidism for the first time during the years 2003-2005.

All new cases of hyperthyroidism > or = 18 years of age were prospectively registered to calculate the total incidence of hyperthyroidism, as well as the incidence of the subgroups: Graves' disease (GD), toxic multinodular goitre and solitary toxic adenoma (STA). Eight specialized units/hospitals in Stockholm County participated in the registration. The participating physicians were all specialists in medical endocrinology, oncology, nuclear medicine or surgery.

During a 3-year period, 1431 new patients of hyperthyroidism were diagnosed in a well-defined adult population (> 18 years of age) of in average 1,457,036 inhabitants. This corresponds to a mean annual incidence of hyperthyroidism of 32.7/100,000. The incidence of GD was 24.5/100,000 per year, toxic nodular goitre was 3.3/100,000 per year and STA was 4.9/100,000 per year.

The total incidence of hyperthyroidism in Stockholm County was found to be 32.7/100,000 per year, of which 75% had GD. There were a higher percentage of smokers among the patients with hyperthyroidism compared with the overall population in Stockholm, but no difference in the frequency of smoking between patients with GD and toxic nodular goitre.