Continuously sustained elimination of iodine deficiency: a quarter of a century success in the Islamic Republic of Iran

Background Iodine deficiency and related disorders were very common in Iran prior to 1996, when universal salt iodization (USI) was implemented and in 2000 Iran was declared iodine deficiency disorders (IDD) free. The aim of this study was to evaluate the adequacy of iodine intake by Iranian households in all 30 provinces of Iran, a quarter of a century after the intervention. Methods A total of 18,000 school-aged children (8-10 years with mean 8.7 +/- 1 year) were included in this study. Urine samples were collected from all children for measurement of urinary iodine excretion and 1800, 210 and 3000 salt samples were randomly collected from the family kitchen, production site of 73 salt factories and distribution circles of 30 provinces, respectively. Results The median urinary iodine concentration (UIC) of participants was 161 mu g/L. The proportion of children with UIC of, 20-49, 50-99 and >= 100 mu g/L were 10.3, 15.9 and 73.7%, respectively. The mean (+/- SD) and median salt iodine values were 28.2 (+/- 12.6) and 31.7 ppm, at the production site, and 31.5 (+/- 13.6) and 29.6 ppm at the distribution circles, respectively. About 80% of factory salts had more than 20 ppm iodine. 98% of households consumed iodized salt, 80% had appropriate salt storage, and 83% of the household salts contained >= 20 ppm. Conclusions Based on the results of this study, Iranian populations are consuming adequate iodine. The well-maintained and monitored USI program has improved the dietary iodine intakes of the population, and the country has achieved all criteria of a well-controlled IDD program.