The function of the thyroid gland is to regulate the body's metabolism. The thyroid gland is prone to several very distinct problems, some of which are extremely common. These problems can be broken down into (a) those concerning the production of hormone (too much, or too little), (b) those due to increased growth of the thyroid causing compression of important neck structures or simply appearing as a mass in the neck, (c) the formation of nodules or lumps within the thyroid which are worrisome for the presence of thyroid cancer, and (d) those which are cancerous. Disorders of the thyroid gland include overactivity, underactivity, tumorous growths and inflammatory lesions. Causes may be dietary or hereditary. Thyroid problems often go undetected because the symptoms are fairly non-specific, eg fatigue, inability to concentrate and modest weight gain.
Thyroid disorders are a known problem among more than 20 million people in the United States. Yet as many as 13 million others may have undiagnosed thyroid dysfunction, clearly affecting their quality of life.
A random survey of thyroid dysfunction in 25,862 apparently healthy and active people found that 9.5 percent of those studied had hypothyroidism, or underactive thyroid, and 2.2 percent had hyperthyroidism, or overactive thyroid.
As mandatory iodine supplementation of salt has proceeded, “The spectrum of thyroid diseases has undergone a significant change ranging from simple goiter to toxic nodular goiter, Hashimoto’s thyroiditis, and thyroid cancer accompanied by the increase in iodine intake, especially for thyroid cancer with an annual increase of 14.51% in China...high iodine intake is likely to lead to occurrence of thyroid diseases, such as Hashimoto’s thyroiditis, nodular goiter, and hyperthyroidism, through a long-term mechanism” (Zhao, H. et al. (2014). Correlation between iodine intake and thyroid disorders: a cross-sectional study from the South of China. Biological Trace Elements Research, 162(1-3), 87-94).