Abstract: Objective To explore the relationship between thyroid-related diseases and iodized salt of coastal residents, so as to provide a scientific theoretical basis for formulating local iodine-supplementation strategy. Methods From July to August 2016, patients with thyroid disease who were admitted to Dongshan County Hospital were selected as case group. Patients without thyroid disease were selected as control group. The individuals of the case and control groups were matched by the same gender and age （ ± 5 years） at a 1∶1 ratio. Conditional logistic regression model was used to analyze the association between salt type and thyroid-related diseases. Results The study included 100 patients with thyroid disease and 100 patients in the control group. The male to female ratio was 0.49∶1 in the both groups. Of the participants, 60% in the case group and 51% in the control group were aged 46-70 years. Multivariate conditional logistic regression showed that after controlling for age, dietary saltiness, per capita kelp consumption, per capita laver consumption, and per capita consumption of fish, shrimp, and crab, the risk of thyroid-related diseases for those who used half iodized salt and half non-iodized salt was 1.75 times that for those who used iodized salt; the risk of thyroid-related diseases for those who drank tea ≥5 times per week was 0.48 times that for those who did not drink tea; the risk of thyroid-related diseases for those with stress was 1.64 times that for those without stress. Conclusions Consumption of half iodized salt and half non-iodized salt, stress and without drinking tea were the risk factors for thyroid-related diseases. The government should strengthen the propaganda of iodine-related knowledge and provide different types of edible salt according to local characteristics.

Key words: Thyroid diseases, Iodine, Sodium chloride, dietary, Factor analysis, statistical