Controlling Iodine Deficiency Disorders

Peterson, S. 2000. Controlling Iodine Deficiency Disorders Studies for Program Management in Sub-Saharan Africa. Acta Universitatis Upsaliensis, Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine 943. 100 pp. Uppsala. ISBN. 91-554-4774-0. Studies were performed to improve iodine deficiency control programs. Goitre rates and cassava processing practices were compared in three Central African Republic (CAR) populations. Short-cuts in cassava processing were associated with elevated urinary thiocyanate and increased goitre rates, suggesting a goitrogenic effect in one population. While improved cassava processing may be beneficial, the priority is to correct the iodine deficiency. The use of the urinary iodine/tiocyanate ratio as indicator of goitrogenic effects was explored using data from Tanzania and CAR. As the ratio can be calculated in four mathematically different ways and has physiological shortcomings, its use is discouraged. Biannual iodised oil capsule (IOC) distribution in a Tanzanian population of 7 million during nine years was studied. Mean distribution coverage was 64%, mean delay of subsequent distribution 1.25 years, and only 43% of targeted person-time was covered. The cost of capsules constituted more than 90% of total program costs. It is cost-effective to invest more funds in communication, support of peripheral staff and supervision. In a highland Tanzanian village, salt iodine content was highly variable compared to national standards. While school-children had adequate urinary iodine, women at delivery and newborns showed signs of inadequate iodine status. Salt iodine concentrations should be monitored during production and distribution down to household level, and iodine status assessed in all vulnerable groups before adjusting recommended salt iodization levels at production. WHO’s 1994 change in palpation goitre definition considerably lowered specificity and increased measured goitre rates by 25% in Tanzanian schoolchildren compared to the previous system. Ultrasound estimation of thyroid volume under rugged field conditions requires considerable human and material resources yet had a precision only slightly better than palpation. In resource poor settings appropriately trained palpators using the 1960 WHO definition of goitre remain optimal for estimating thyroid size until precision and cost of ultrasound has improved. Monitoring of process indicators needs to be an ongoing priority activity, separate from periodic evaluations of impact.