In the developing countries of Africa, many children are at high risk for both goiter and iron-deficiency anemia (IDA). Because iron (Fe) deficiency can have adverse effects on thyroid metabolism, Fe deficiency may influence response to supplemental iodine in areas of endemic goiter. Therefore, our aims were to determine: 1) if goitrous children also suffering from IDA could respond to oral iodine supplementation; and 2) if Fe supplementation in goitrous children with IDA would improve their response to oral iodized oil and iodized salt. First, we compared the efficacy of oral iodized oil in two groups of goitrous children: a nonanemic group vs. an IDA group. The therapeutic response to iodized oil was impaired in the goitrous children with IDA. Second, an open trial of Fe treatment in goitrous children with IDA improved their response to oral iodized oil. Finally, in a randomized double-blind trial, goitrous, Fe-deficient children consuming iodized salt were given Fe supplementation or placebo. Fe supplementation improved the efficacy of the iodized salt. In these studies, both anatomic (thyroid size) and biochemical (TSH, T4) measures indicated that iodine significantly improved thyroid function in the nonanemic children compared to the Fe deficient children. Iodine was less efficacious in children with lower Hb at baseline and in those with a poorer response to Fe. The data suggest that a high prevalence of IDA among children in areas of endemic goiter may reduce the effectiveness of iodine prophylaxis.
