The epidemiology of iodine deficiency disorders (IDD) in Yemen.

Abstract

This first nationwide survey was undertaken to estimate the prevalence rates and severity of iodine deficiency disorders (IDD) and the proportion of households consuming iodized salt. The country was stratified into two ecological zones and 30 clusters (primary schools) from each zone, including the required numbers of pupils, were selected randomly. A subsample of pupils provided urine and salt samples for the determination of urinary iodine excretion (UIE) and presence of iodate, respectively. Yemen. There were a total of 2984 pupils aged 6-12 years of whom 2003 were boys and 981 girls. The majority (1800) pupils were from the lowland/coastal areas (zone II) and the rest (1184) from the mountainous regions (zone I). The total goitre rates (TGR) in the whole country, zones II and I were 16.8%, 31.1% and 7.4%, respectively. The TGR in zone I for males was 32.8% and 27.3% for females, while in zone II the corresponding rates were 8.1% and 5.9%, respectively, and the differences were not statistically significant. Only three cases of visible goitres were encountered. The median UIE levels in zones I, II and the whole country were 13.6, 18.9 and 17.3 microg dl-1, respectively. Based on UIE cut-off points recommended by WHO, IDD was severe in 4.7% of pupils in zone I and 2.6% in zone II. Mild and moderate IDD were found in 18.5% and 8.7% of the pupils respectively. Nearly 70% of the surveyed pupils had UIE values of >/= 10 microg dl-1 (no deficiency). Girls had relatively better iodine nutrition as suggested by higher levels of median UIE. In addition, across all age groups median UIE values were above 10 microg dl-1. Over half of the households consumed iodized salt. Since the introduction of universal salt iodization in 1996 both the prevalence and severity of IDD in Yemen were reduced markedly and Yemen can now be classified as a country with a mild IDD problem. However, the low level of households consuming iodized salt may hamper the goal of IDD elimination.