OBJECTIVETo compare the effects of three different iodine interventions on the speed of normalization of enlarged thyroid gland.

METHODSSchoolchildren aged 8 - 10 years were randomized divided into one of three groups: group A was given iodized salt by researchers with an iodine concentration of 25 mg/kg; group B used iodized salt purchased from the market; and group C was similar to group B with additional intake of iodized oil capsules containing 400 mg iodine at the beginning of the study. Salt iodine content was measured bimonthly for 18 months and indicators of iodine deficiency were measured at baseline and 6, 9, 12 and 18 months thereafter.

RESULTSThe prevalence of goiter measured by ultrasound, based on the World Health Organization (WHO) body surface area reference > 97(th) percentile, was 18% at baseline and declined to less than 5% by 12 month in groups A and C respectively, and to 9% after 18 months in group B. Rates of goiter were similar by palpation or by ultrasound. The median urinary iodine was 94 micro g/L at baseline and increased in all groups to > 200 micro g/L at the 6-month follow-up.

CONCLUSIONSIn this sample of schoolchildren with initially low or moderate level of iodine deficiency, the group receiving salt with 25 mg/kg (group A) recovered from iodine deficient on all indicators after 18 months of study. However when the iodine content of salt was floating, as seen in group B, the sizes of thyroid did not yet achieve normal status by 18 months.