In 1991, a rapid assessment survey was conducted in the mountainous regions of Yemen1 , which showed a high prevalence of goitre in school children. According to this survey, the prevalence of total goitre rate (TGR) in the whole Yemen was estimated as 32%. In November 1998, two years after introducing the USI strategy, the IDD National Survey was conducted.
The survey showed that the prevalence of TGR was at 16.8% and the median urinary iodine excretion was 17.3µg/dl2 . Unfortunately, no recent valid data are available. It was identified that there was an urgent need for a national survey using urinary iodine excretion as main indicator.
The 1991 rapid assessment indicated that grade-2 goitre prevalence among school girls was 16 – 55%. Unexpectedly, using the indicator of TSH, 63% of low land Tihama children was found to be iodine deficient3 . Unlike Tihama, goitre prevalence among preschool children in southern and eastern governorates was 0.15%4 . It was understood that IDD exists in lowland and coastal areas if people living there do not regularly consume seafood and since iodine in soil can easily be drained. The low prevalence of goitre in southern and eastern governorates is understood to be due to the traditional regular consumption of fish. The 1998 survey indicated that TGR in mountainous governorates/districts was at 31.1% and only 7.4% in sub mountainous and lowland governorates/districts. The prevalence of goitre by gender were at 18.1% and 14.1% among males and females, respectively.
The main underlying cause of IDD is lack of iodine in food eaten. Existence of iodine in food is not depending on the type of food but on the presence of iodine in the environment where food grown or cultivated. Because of iodine draining from the soil, the only natural iodine food source is seafood. Salt iodization is an evidence-based intervention that effectively reduces iodine deficiency at a population-level.