An Iodine Balance Study in Chinese School-age Children

Context Few iodine balance studies have been conducted in school-age children. Objective This study aimed to conduct an iodine balance study in school-age children. Methods We measured daily iodine intake, excretion, and retention for 3 consecutive days without any dietary interventions in school-age children. Linear mixed-effects models were used to fit the relationship between total iodine intake and iodine retention. Results 29 children aged 7-12 years (mean age 10.2 +/- 1.4 years) with normal thyroid function and thyroid volume were recruited. The 0 balance value (iodine intake = iodine excretion, iodine retention = 0 mu g/day) shifted with iodine intake in an iodine sufficient population. The 0 balance value for school-age children with an iodine intake of 235 (133, 401) mu g/day is 164 mu g/day. Children aged 7-12 years with iodine intake >400 mu g/day were almost all in a positive iodine state. Conclusion An iodine intake of 235 (133, 401) mu g/day for children aged 7-10 years achieved a 0 balance value of 164 mu g/day. Long-term iodine intake of >400 mu g/day is not recommended.