For the Media General Statistics
The statistics and comments offered here are updated annually and represent our best effort to provide you with accurate information about the prevalence of thyroid disorders in various populations. Remember that these data usually refer to the American population, and would be quite different in countries where the amount of iodine in the diet in insufficient to make normal amounts of thyroid hormone. Even in developed countries of central Europe, years of iodine deficiency have produced a far greater incidence of goiter and thyroid nodules which continues today despite the fact that most Europeans now have a diet that contains a normal amount of iodine.
This data is based on statistical information gathered for Your Thyroid: A Home Reference by Drs. Wood, Cooper, and Ridgeway and periodically modified according to new U.S. Census Bureau information. It is more conservative than the numbers extrapolated from the "Colorado Study" (Canaris et al, 2000). Please Prevalence of Thyroid Disease in the United States: Considerations for Recognition and Prevention of Complications by Dr. David Cooper for more information.
Between 20 and 25% of the population in the United States probably have a genetic tendency toward autoimmune disorders. Many of these people develop hyperthyroidism or hypothyroidism. Among these people the first sign of thyroid failure is an increase in the blood level of thyroid-stimulating hormone (TSH), while a sub-normal TSH level suggests hyperthyroidism.