Research in Medicine

Background : Following previous reports of impaired physical and intellectual growth, hearing deficit, hypothyroidism, and hyperendemic goiter in Kiga, and the administration of iodized oil injection, this study was conducted to evaluate if the effect of the injection could be sustained by iodized salt supplementation.

Materials and methods : In 1989, one ml of iodized oil solution containing 480 mg of iodine was injected in 198 schoolchildren aged 8 to 14 years in Kiga. Four years later, in 1993 iodized salt consumption was begun and has been continued. Serum thyroid hormones, RT₃U and TSH were measured before and 3, 4 and 6 years after intervention (1989, 1992, 1993 and 1995). Assessment of urinary iodine was performed at the same intervals mentioned above by Foss method.

Results : Prior to the injection, 94% of the subjects had grade 2 goiters 4 years after injection 30% and two years after iodized salt consumption 56% were agoiterous (p<0.001). Urinary iodine was 11.4±19.8 before and increased to 93±66 and 92±34μg/L, 3 and 4 years after intervention. Two years after iodized salt consumption it was 161±34μg/L (p<0.001). Mean serum Increased T4 level was observed following the iodized oil injection and continued after iodized salt consumption. Serum TSH was 20.3±22.8, 2.1±1.9, 2.5±1.6 and 2.9±1.7 mU/L before and 3, 4 and 6 years after the beginning of study, respectively. All children were euthyroid at 3, 4 and 6 years of study.

Conclusion : Findings show benefits of iodized oil administration in decreasing goiter size and in reversing abnormal thyroid function. These effects are sustained by iodized salt consumption in schoolchildren previously hypothyroid due to iodine deficiency.