Prevalence of endemic goiter and urinary iodine in 6-11 year old students in Yazd province: 10 years after salt iodization programme

Introduction: Iodine deficiency disorders (IDD) are among the most important epidemic disorders in the world and also in our country. The surveillance of IDD may be implemented to assess the prevalence of IDD, identify high risk areas for intervention and monitor and evaluate IDD control programmes, such as salt iodization. The objective of this study was to determine total goiter rate (TGR) and urinary iodine in 6-11 year old students in Yazd province and related cities 10 years after salt iodization programme. Materials and Methods: In this prevalence study, 4755 primary school students (2948 boys and 1807 girls) aged 6-11 were selected by multistage “probability proportionate to size” (PPS) cluster sampling in Yazd province. Thyroid examination and goiter classification were made according to WHO standard protocol by two trained physicians. Urine and household salt samples were collected from one-thirteenth of the total population. Urinary iodine was determined by digestion method. Salt iodine was determined by rapid test kit. Results: TGR was 40.9% in Yazd province (Girls 41.8% and boys 40.3% p>0.05). Prevalence of goiter grade 1 and grade 2 were 38.6% and 2.3%, respectively. These figures were 39.1% and 2.7% for girls and 38.3% and 2% for boys, respectively. The rate of goiter was not significantly different between two sexes (p=0.2). Overall mean of the urinary iodine in province was 264±123 μg/L and corresponding mean in girls and boys were 236±118 μg/L and 281±123 μg/L, respectively which were significantly different (p=0.001). In general, 10.5% of Yazd population had urinary iodine concentrations under 100 μg/L, 24.5% were in ideal range (100-200 μg/L) and 65% were higher than 200 μg/L. In general, 6% of household salt samples did not have iodine, 1.1% had 8ppm, 6% 15ppm and 86.8% had above 30ppm. Thus, approximately 94% of salt samples contained iodine. Conclusion: The results of this study indicated that TGR, especially goiter grade 2, has markedly decreased and according to urinary iodine status, not only mean urinary iodine was elevated, but also was higher than ideal range of WHO. Thus, according to this index, it can be concluded that Yazd province has been IDD free since 2002.