The Impact of Various Iodized Salt Doses Intervention on Iodine Status and Thyroid Function on Primary School Children

Abstract

Background. There were some debate regarding iodized salt dosages (SNI>30 ppm) indicating excess of iodine in some areas in Indonesia. Previous studies have not yet define appropriate and effective iodine content in salt that ensure safe iodine status for the community. Objective. This study aims to define iodized dosage in salt that can effectively guarantee the urine iodine levels and normal thyroid function in elementary school children. Method. The study was conducted in Kepil Subdistrict,Wonosobo District for ten months. The subjects were 176 children aged 6-12 years chosen using randomized block design with eight blocks. This is a population based double-blind RCT. Each intervention groups given iodized salt dosage of 15-25 ppm; 25-35 ppm; 35-45 ppm; 45-55 ppm KIO3 respectivelly for four months. Research variables were urinary iodine excretion (24-hours urine samples), thyroid function, nutritional status, iodine sources food consumption, goitrogenic and iodized salt consumption. Results. The median value of urinary iodine excretion (UIE) was still within the optimal limits (100-300 ug/l): 222 ug/l (pre study) and 238 ug/l (post study). The median value of UIE and TSH levels were not significantly different between groups or between pre and post study. The risk of iodine deficiency and excess of 8.0% and 26.7% respectivelly at pre study; to 7.4% and 31.2% post study. Subjects with high TSH and low TSH level was found after four months of intervention. Thyroid function based on the assessment of TSH and FT4 levels simultaneously not found the incidence of overt overt hypothyroidism and overt hyperthyroidism. There were no overt hypothyroidism and overt hyperthyroidism, however, there were 4% subclinic hypothyroid and 1.7% subclinic hyperthyroidism in post study. Conclusion. Iodized salt (KIO3) intervention of 15-55 ppm for four months was generally able to provide normal urine iodine and thyroid function on elementary school children.