Factors relating to urinary iodine concentration of pregnant women in Thailand

Abstract

This cross-sectional study was conducted to assess factors relating to urinary iodine concentration (UIC) of pregnant women in Thailand. Subjects were delivered at government hospitals in 8 provinces. These were selected from 29 provinces included in the surveillance system for iodine deficiency in pregnant women of the Ministry of Public Health during 2005-2007. There were 2 provinces from each of the 4 regions of the country i.e. north, northeast, central, and south. There were 800 subjects, 100 from each province. Around 65 percent of them (531 subjects) used iodized salt as iodine deficiency disorders (IDD) prevention measure. Median UIC was 9.19 μg/dl. Only 14% of pregnant women (112 out of 800 subjects) had appropriate UIC (in the range of 15.00 – 24.99 μg/dl). 69.5% of pregnant women (556 out of 800 subjects) had UIC less than adequate level (15 μg/dl). Iodine concentration in household salt was measured by test kit (I-Kit) developed at Mahidol University. 68.1% of household salt samples (545 out of 800 samples) had iodine concentration in the range of 30–100 ppm. Relationships between UIC and independent variables were analyzed. In bivariate analysis, both salt iodine and use of iodized salt for IDD prevention were statistically significantly positively associated with UIC (p<0.001). There were also significant differences by region and province. Region and province had statistically significant relationships with UIC (p<0.001). However, in multivariable linear regression analysis, only region and province achieved significance (p<0.001). UIC was higher in the southern region than in other regions. Study findings suggest that IDD prevention measures in Thailand should be reconsidered. To be effective, these measures should be appropriate to Thai culture and also local cultures of each region of the country. In general, fish sauce and a wide variety of food can be produced to be iodine sources for Thai people. However, appropriate sources of iodine intake for pregnant women should be studied further. The data in this study were subject to uncertainty, so further research is needed before policies are changed. For further study, UIC of pregnant women and UIC of children should also be evaluated for association.