The Establishment Of I-FFQ And Its Application In Evaluation Of Iodine Nutrition In Adults

Objective1.To assess the validity and reproducibility of the I-FFQ and verify the feasibility of I-FFQ in the iodine nutrition evaluation of adults.2.Simplified and optimized the I-FFQ so that it can be better applied to iodine nutrition evaluation.3.To evaluate the iodine nutrition status of adults in Tianjin.MethodsThe study was conducted in Health Service Center of Yangjiabai county in Binhai district and Chunhua Street Community Health Center in Hedong district.The enrolled criteria of subjects was as follows:aged above 18 years old,Han nationality and lived in Tianjin at least 5 years,no recording of Iodine-containing contrast agent examination and using iodine containing drugs,besides,pregnant women and lactating women were excluded.The research program contained adopting basic information,collecting morning spot urine,blood sample,ultrasound determination of thyroid and Dietary survey,et al.The urine sample was determined by As(Ш)–Ce4~+catalytic spectrophotometry.TSH,TPOAb and TGAb were determined and Serum FT3,FT4were determined when TSH level is abnormal.And thyroid goiter rate and thyroid nodules prevalence was calculated.The I-FFQ and 3-day dietary record were conducted by trained investigators.In order to assess the Retest reliability,college students were selected to conduct twice I-FFQ survey two weeks apart under the guidance of unified training investigators at Tianjin Medical University.Results1.There were 1989 and 2033 subjects completed I-FFQ and 3-day records respectively.The result of I-FFQ and 3-day records were 336(299,381)μg/d和283(253,322)μg/d respectively.2.The results of I-FFQ and three-day records significantly correlated(r=0.673,P<0.001).The result of kappa test shows good consistency(Kappa=0.583,P<0.001).Bland-Altman plots analysis shows the mean variation of I-FFQ and three-day dietary questionnaire was 44.6μg/d,the consistency range was-85.0~174.2μg/d,there were 4.9%(91/1849)of the subjects were out of the consistency range.3.In the assessment of reproducibility,the correlation between I-FFQ1 and I-FFQ2 intakes was significant(r=0.826,P<0.001),The result of the Kappa test of the twice I-FFQ indicating a good agreement(Kappa=0.762,P<0.001).the median of the absolute value of difference of the twice I-FFQ was 20.05μg/d,the quartile was6~34μg/d.4.The mean difference before and after optimization was 2μg/d,Kappa test results showed a good agreement(Kappa=0.972,P=0.013).1.2494urine sample were collected.5.The median urine iodine concentration(MUIC)of whole population is117μg/L,in a iodine adequate state,there were 35.5%of the subjects whose UIC was<100μg/Land 10.4%of the subjects whose UIC was>300μg/L.MUIC of males was higher than that of females(Z=-3.733,P<0.001),MUIC of Suburban residents was higher than that of Urban residents(Z=-10.376,P<0.001).6.2614 subjects accepted thyroid B-ultrasound examination.The thyroid volume of males was larger than that of females(10ml vs 8ml,Z=-17.332,P<0.001),the whole thyroid goiter rate was 2.2%,and thyroid nodules prevalence was 26.0%.7.2637 blood sample were coleected.The prevalence of Hypothyroidism was 1.4%,prevalence of subclinical Hypothyroidism was 8.4%,prevalence of Hyperthyroidism was 0.8%,prevalence of subclinical Hyperthyroidism was 0.4%.Positive rate of TPOAb and TGAb was 10.4%and 12.0%respectively.8.the correlation between I-FFQ and UIC is slight(r_s=0.072,P<0.01).no statistical significance was found about the prevalence of thyroid nodules among different iodine intake groups,nor about the thyroid volume,no statistical significance was found about correlation between I-FFQ and serum TSH.Besides,the positive rate of TPOAb and TGAb was highest when iodine intake was<120μg/d.Conclusion1.Assessment of I-FFQ revealed a satisfactory level of validity and reproducibility,the adults I-FFQ may be indicated as a tool for the assessment of iodine intake in adults.2.I-FFQ before and after optimized were highly consistent,so the optimized I-FFQ can be used for future iodine surveys for adults.3.According to the result of this survey,Adults in Tianjin were in iodine adequate state,But there were still some people at the risk of iodine deficiency or iodine excess.