Abstract:

Objective By comparing the detection rates of subclinical thyroid diseases in women(pregnant,lactating and child-bearing age) between iodine deficient regions (supplied iodized salt) and water-borne iodine excess regions(consumed non-iodized salt),and to find the different prevalence of subclinical thyroid disease between two regions under their different iodine source and iodine levels,and to provide reference for screening susceptible population with iodine-related thyroid diseases.Methods The iodine deficiency but salt iodine surpplying regions were selected from six provinces in our country,the local people who were pregnant women,lactating women and 18 to 45 years old women of child-bearing age,a total of 991 cases were investigated.The iodine nutrition levels of the pregnant women were grouped by <150,150-249,and ≥500 μg?L-1;the iodine nutrition levels of the lactating women were grouped by <100 and ≥100 μg?L-1.The high water-iodine regions in Shanxi Province were selected,and according to the water-iodine levels 50－99,100－149,149－299,and more than 300  μg?L-1 four regions were selected; 20 cases of three kinds of people mentioned above were selected in each region,a total of 241 cases.The blood and urine samples were collected,and the serological thyroid function indexes were detected by chemiluminescence immunoassay method or radioimmunity method,and the urine-iodine was detected with cerium catalytic spectrophotometric method.Results In iodine deficient regions and water-borne iodine excess regions,the concurrence rates of subclinical hypothyroidism(hypothyroidism for short) and thyroid antibody positive of women were 2.32% and 4.98%,respectively;accounting to about 1/3 to 1/2 of those subclinical hypothyroidism population.The prevalence rates of subclinical thyroid diseases in the women population between the two regions were 27.55% and 34.85%,respectively;nearly accounting for 1/3 of the women population.The subclinical hypothyroidism detection rates of the three populations in high water iodine regions were significantly higher than those in iodine deficient regions(P<0.05).The lactating women’s detection rates of thyroid antibody positive and subclinical hypothyroidism with antibody positive in high water iodine regions were significantly higher than those in iodine deficient regions(P<0.05).With different iodine sources,when took appropriate iodine,there was no statistical difference of the detection rates of subclinical thyroid diseases among three kinds of women(P>0.05).With the increase of iodine exposure levels,the prevalence of women who suffered from subclinical hypothyroidism and thyroid antibody positive was increased,the coincidence rate was  also increased.The detection rates of low T4 concentration and total subclinical thyroid disease of pregnant women in iodine nutrition <100  μg.L^-1group were significantly higher than those in  iodine nutrition 250－499  μg.L^-1 group (P<0.05).The detection rates  of low T4 concentration and total subclinical thyroid disease of lactating women in iodine nutrition <100  μg.L^-1group were significantly higher than those in  iodine nutrition >100  μg.L^-1group (P<0.05).Conclusion When the iodine intake is appropriate,iodine intakes from salt or from water have no effect on subclinical thyroid diseases.When the iodine intake increases,the prevalence of subclinical thyroid diseases will increase too.

Key words: iodine deficiency, high water-iodine, women, subclinical thyroid diseases, detection rate