Etiology and epidemiology of thyroid nodules recognition      YU Xiao-hui， SHAN Zhong-yan. Department of Endocrinology, the First Affiliated Hospital of China Medical University, Shenyang110001，China
Corresponding author： SHAN Zhong-yan， E-mail：shanzhongyan@hotmail.com
Abstract    Thyroid nodules are common in clinical practice. Epidemiologic studies have shown the prevalence of palpable thyroid nodules to be approximately 5% in women and 1% in men living in iodine-sufficient parts of the world. In contrast, high-resolution ultrasound can detect thyroid nodules in 19%-67% of randomly selected individuals with higher frequencies in women and the elderly. The clinical importance of thyroid nodules tests with the need to exclude thyroid cancer which occurs in 5%-10%. Studies have shown the prevalence of thyroid nodules is associated with age, sex, radiation exposure history, family history and other factors. And iodine intake is an important factor. Some studies showed that prevalence of thyroid nodules increased with the decreasing iodine intake. Recently the incidence of thyroid cancer has increased gradually.