['In many developing countries, children are at high risk of both goiter and iron deficiency anemia. Iron deficiency adversely affects thyroid metabolism and may reduce the efficacy of iodine prophylaxis in areas of endemic goiter.', 'The aim of this study was to determine whether iron supplementation in goitrous, iron-deficient children would improve their response to iodized salt.', "We conducted a randomized, double-blind, placebo-controlled trial in 5-14-y-old children in Côte d'Ivoire. Goitrous, iron-deficient children (n = 166) consuming iodized salt (10-30 mg I/kg salt at the household level) were supplemented with either iron (60 mg Fe/d, 4 d/wk for 16 wk) or placebo. At 0, 1, 6, 12, and 20 wk, we measured hemoglobin, serum ferritin, serum transferrin receptor, whole-blood zinc protoporphyrin, thyrotropin, thyroxine, urinary iodine, and thyroid gland volume (by ultrasonography).", 'Hemoglobin and iron status at 20 wk were significantly better after iron treatment than after placebo (P < 0.05). At 20 wk, the mean reduction in thyroid size in the iron-treated group was nearly twice that in the placebo group (x +/- SD percentage change in thyroid volume from baseline: -22.8 +/- 10.7% compared with -12.7 +/- 10.1%; P < 0.01). At 20 wk, goiter prevalence was 43% in the iron-treated group compared with 62% in the placebo group (P < 0.02). There were no significant differences between groups in whole-blood thyrotropin or serum thyroxine at baseline or during the intervention.'] Does treatment of iron deficiency in goitrous children improve the efficacy of iodized salt in Côte d'Ivoire?