Study On The Saliva Iodine As An Indicator For Evaluation Of Iodine Nutrition In Adult

Objective1.To explore the representative using morning SIC(saliva iodine concentration)to reflect the population of iodine nutrition by comparing morning SIC with urinary iodine levels of 24 hours and morning UIC(urine iodine concentration)in adult respectively.2.To explore seasonal changes and changes within a day of SIC by measuring SIC in different seasons and different sampling time one day,and deduce the correction coefficients that can be used to carry out SIC at different time points in adult to ensure the comparability of SIC in actual sampling work.MethodStudy 1:relationship between morning SIC and 24h urinary iodine level in adult:Based on the inclusion criteria,172 adults were recruited,aged 22.07±2.30y,and 2ml salivary samples at morning(7:00)and 24h urine samples(7:00-7:00)were collected.Statistical methods:difference analysis,correlation analysis,Kappa consistency test,and validity test were used to analyze the relationship between morning SIC and 24h urinary iodine level.Study 2:relationship between morning SIC and morning UIC in adult:Based on the inclusion criteria,242 adults were recruited,aged 21.95±2.22y,and 2ml morning salivary samples(7:00)and 4ml morning urine samples were collected.Statistical methods:difference analysis,correlation analysis,and Kappa consistency test were used to analyze the relationship between morning SIC and 24h urinary iodine level.Study 3:seasonal changes of SIC and within-day changes of SIC in adult:(1)seasonal changes in SIC:Based on the inclusion criteria,82 adults were recruited,aged21.77±2.31y,2ml morning salivary samples of four seasons were collected.Statistical methods:repeated measures ANOVA,and and?~2 analysis method were used.(2)within-day changes of SIC:Based on the inclusion criteria,424 adults were recruited,aged 20.54±1.52y,and 2ml salivary samples at three time points(7:00,10:30 and16:30)were collected.Statistical methods:mixed linear model statistical method and Wilcoxon signed-rank test were used.Determination of saliva iodine and urine iodine were determined by inductively coupled plasma mass spectrometry(ICP-MS).Results1.comparison between morning SIC and 24h urinary iodine levels:(1)morning SIC(7:00)was lower than that 24h-UIC(121.69?g/L vs 162.55?g/L,Z=2.858,P=0.000).(2)correlation analysis:there was a positive correlation between morning SIC(7:00)and 24h-UIC(r was 0.594,P=0.000);there was a positive correlation between morning SIC(7:00)and 24h-UIE(r was 0.606,P=0.000).(3)consistency test:The Kappa consistency value of morning SIC(7:00)and 24h-UIC was 0.304;The Kappa consistency value between morning SIC(7:00)and the daily iodine intake was 0.294.(4)authenticity test:regard the intake of iodine one day as the gold standard to evaluate the individual iodine nutritional status,sensitivity was 64.4%,specificity was 62.2%,and the Youden index was 0.266 of morning SIC(7:00).2.comparison between morning SIC and morning UIC:(1)difference test:morning SIC(7:00)was lower than morning UIC(115.71?g/L vs 160.75?g/L,Z=2.991,P<0.05).(2)correlation analysis:morning SIC(7:00)was positively correlated with morning UIC(r was 0.536,P=0.000).(3)consistency test:The Kappa consistency value between morning SIC(7:00)and morning UIC was 0.426.3.seasonal changes in SIC and within-day changes in SIC in adult:(1)seasonal changes in SIC in adult:(1)difference test:the difference between SIC in four seasons had no statistically significant(F=2.341,P=0.082).(2)The seasonal distribution of SIC:The distribution of SIC in four seasons was consisten(?~2=6.471,P=0.373).(2)within-day changes of SIC in adult:(1)SIC between three time points showed no significant difference(F=0.452,P=0.636).(2)The correction coefficients for 10:30saliva iodine and 16:30 saliva iodine to corrected to 7:00 saliva iodine level were0.9961 and 1.0004,respectively;and the average deviations between corrected“7:00SIC”and actual“7:00 SIC”were 33.46?g/L and 36.73?g/L,respectively.Conclusions1.SIC can be used to reflect the population iodine nutrition status in adult.2.SIC have no seasonal changes and within-day changes3.Correction coefficient can be used to convert SIC at different time points,but it should be combined with the normal range of saliva iodine level before it can be used in actual field surveys.