The Prevalence of autoimmune thyroiditis after universal salt iodisation in Sri Lanka

Abstract

INTRODUCTION: Sri Lanka is endemic for goiters. Iodine deficiency is thought to be the main cause. The global iodisation programme was implemented in the country in 1995. Several studies done in school children have shown a reduction in the goiter prevalence (3.8%) in the initial post iodisation period. An island wide, community based study was carried out to study the prevalence of goiters. METHODS: A multistage cluster sampling method was used. Examination of goiters was done by two trained investigators and graded according to the WHO grading. Fine needle aspiration cytology of the goitres was also undertaken in the field. A sample of urine was collected from all participants. In a random sample of 153 individuals with a goiter, serum was checked for anti thyroid peroxidase antibodies. RESULTS: Out of 5200 individuals screened, 426 had a clinically detectable goiter. Adjusted prevalence rate was 6.8%. Both serological and cytological evidence of autoimmune thyroiditis was seen in 19.6% of goiters. Mean urinary iodine concentration was 235 μg/l range 11.1 - 425 μg/l). Association between elevated antithyroperoxidase antibodies and median urinary iodine concentration was significant. CONCLUSION: Goiter prevalence in Sri Lanka has increased after an initial drop following the iodisation. A significant proportion of goiters is due to AIT. Urinary excretion of Iodine in the community is high and has a positive correlation with the prevalence of aTPO anti vodies. Increase in AIT due to a high Iodine intake may account for the rise in goiter prevalence.