The Research On The Prevalence Of Thyroid Nodules And Its Influence Factors In Different Iodine Nutrition

Objective:1.To explor the prevalence of thyroid nodules in different levels of iodine nutrition area.2.To compare thyroid function in thyroid nodules group and control group without thyroid nodules.3.To explor the influencing factors of thyroid nodules by the cross sectional study,and then to explore the related factors of thyroid nodules by 1:1 matched case-control study.Method:We took a typical survey in Zhangpu County of Zhangzhou city(coastal area covered with non iodized salt),Xiangan District of Xiamen city(coastal area coverd with iodized salt),and Zhangping County of Longyan City(inland area covered with iodized salt).The number of every survey point were 653,648,and645.In the survey points we collected salt samples and conducted a questionnaire,examined the thyroid and collected random urine on participants;Then from the cross-section study,according to the inclusion and exclusion criteria,screened case control object,and collected the venous blood.Urine samples were detected by the "arsenic cerium catalytic spectrophotometric method"(WS/T107-2016),the detection of thyroid function by access2 immunoassay(CLIA).Data was inputted by Epidata3.1 with double data in real time.We used the SPSS21.0 software to analyze the statistics.The urinary iodine level compared with rank sum test,the horizontal distribution of major risk factors of thyroid nodules by Chi-square test,multivariate Logistic regression analysis of factors of thyroid nodules influence;case-control study using the Wilcoxon rank sum test between case group and control group on thyroid function indexes.Result:1.Cross sectional study1.1 General situation of the studyThe study investigated 1946 permanent residents in Fujian Province,including288 children,1255 middle-aged,and 403 elderly people,accounting for 14.8%,64.5% and 20.7% of the population respectively.Zhangpu,Xiangan and Zhangping investigated 653 people,648 people and 645 people respectively.1.2 Iodine nutrition status by RegionZhangpu,Xiangan,Zhangping,the coverage rate of iodized salt were 0%,89.5% and 100%;the rate of qualified iodized salt were 0%,71.60%,96.8%;the median salt iodine were 0mg/kg,22.3mg/kg,25.0mg/kg.The median urinary iodine of Zhangpu was 83.9μg/L,the median urinary iodine of Xiangan was155.0μg/L,the median urinary iodine of Zhangping was 238.35μg/L.The Kruskal-Wallis H test the median urinary iodine between regional differences were statistically significant.1.3 Distribution characteristics of high risk thyroid nodules in different iodine nutrition regionsIn areas with different iodine nutrition level of male and female high-risk nodules accounted for the proportion of the total number of nodules showed no significant difference(P > 0.05);different age high-risk nodules,which accounted for the proportion of the total number of nodules is different,the difference was statistically significant(P < 0.05),high-risk nodules in the age of 66-75 in nodules in the proportion reached the peak 32.1%.1.4 Distribution characteristics and prevalence of thyroid nodules in different iodine nutritional regionsThe prevalence of thyroid nodules,solitary nodule,multiple nodules and nodular goiter in mild insufficient iodine intake area were 20.2%、8.7%、9.8%、1.7% respectively.In adequate iodine intake area,the prevalence of thyroid nodules,solitary nodule,multiple nodules and nodular goiter were 22.5%、11.0%、710.3%、1.2%.In excess iodine intake area the prevalence of thyroid nodules,solitary nodule,multiple nodules and nodular goiter were 19.5%、8.1%、10.5%、0.9%.By gender,Neither the male’nor the females’ thyroid nodules,solitary nodule,multiple nodules prevalence rate were showed no significant difference in different levels of iodine nutrition area(P > 0.05).According to the population division,there were no significant differences in the incidence of thyroid nodules,solitary nodules and multiple nodules between different levels of iodine nutrition area(P > 0.05).1.5 The influencing factors of thyroid nodules in cross-section studyThe factors that may influence the prevalence of thyroid nodules were gender,age,degree of education,present or previous thyroid disease,diabetes mellitus.1.6 Ultrasonographic features of thyroid nodules in different iodine nutritional regionsIn different levels of iodine nutrition area,the common features with B-ultrasound of the thyroid nodules were unaccompanied,clear boundary,no capsule.In mild insufficient iodine intake area and adequate iodine intake area,the thyroid nodules with low echo area,decreased blood supply,In excess iodine intake area,the thyroid nodules with mixed echo,no blood supply.In mild insufficient iodine intake area and excess iodine intake area were most solitary nodules,but in adequate iodine intake area were most multiple nodules.2 1:1 matched case-control study2.1 Comparison of thyroid function and thyroid disease in case group and control groupIn mild insufficient iodine intake area,excess iodine intake area and whole population,the results both showed that the Tg and FT4 concentrations in the case group were higher than those in the control group,the difference was statistically significant(P < 0.05).In adequate iodine intake area showed that the Tg concentrations in the case group were higher than those in the control group,the difference was statistically significant.Two groups of thyroid disease detection rate and distribution level of FT4 showed no significant difference(P > 0.05).2.2 Comparison of thyroid function indexes between high risk group and controlgroupThe Tg level in the high-risk group was higher than that in the control group,the difference was statistically significant,there were no significant differences in other indicators.2.3 1:1 matched case-control study of thyroid nodulesConditional Logisitic multivariate regression analysis showed that the history of thyroid disease,Tg and TgAb were statistically correlated with thyroid nodules.Conclusion:1.The iodine nutrition level in Fujian province is appropriate,and there is no evidence that thyroid nodules are related to the consumption of iodized salt and iodine nutrition level;2.The prevalence of thyroid nodules in areas with defferent iodine nutrition level was 20.2%,22.5%,19.5%.the prevalence of thyroid nodules in women was higher than that in males’,the prevalence of nodules increased with age,the peak prevalence was 56-65 years old,We should strengthen the health education of women and the elderly,To prevent and treat of high incidence of thyroid nodules;3.The history of thyroid disease,the high level of TgAb were the risk factors for thyroid nodules,the lower level of Tg,the less risk to have thyroid nodules.Those with thyroid disease and high TgAb level should be strengthened to follow up and be alert to malignant lesions of thyroid nodules.