Thai government has introduced using iodized salt in foods and the addition of iodine to fish sauce, soy sauce and salt brine. It is uncertain these changes will differently affect in various target groups. This study aimed to evaluate iodine status of nationally representative school-aged children (SAC) and women of reproductive age (WRA).
A cross-sectional study was conducted in 2012 among 1110 pairs of Thai SAC (9.4±1.9 y) and WRA (36.5±6.5 y) living in the same household. Children were selected using a PPS sampling from Bangkok and central, north, northeast, and southern regions. Spot urine samples were analyzed for urinary iodine concentration (UIC) and dried blood spots (DBS) were analyzed for thyroid stimulating hormone, total thyroxine, and thyroglobulin concentrations.
SAC had nearly twice of median UIC compared with WRA (261.6 vs.141.5 µg/L). Based on WHO categories of UIC, lower prevalence of iodine deficiency (ID) was shown among SAC (10.2% for SAC vs. 33.7% for WRA). Additionally, 1/3 of SAC reported having excess iodine intake (UIC=300 µg/L). Among SAC and WRA who having median UIC <100 µg/L, there were no subclinical and overt hypothyroidism. Whereas, prevalence of isolated hypothyroxinemia was higher in SAC (49.8%) compared to WRA (15.5%).
Although iodine fortification has been implemented in Thailand, within the same household, WRA had lower iodine intake while SAC showed a trend of iodine excess. Hence, regular monitoring of iodine status in various target groups is warranted to ensure adequate iodine nutrition and prevent iodine excess.