The association of urine markers of iodine intake with development and growth among children in rural Uganda: a secondary analysis of a randomised education trial

OBJECTIVE: We examined associations of urine iodide excretion, proxy for iodine intake, with child development and growth. DESIGN: This is a secondary analysis of a 1:1 cluster-randomised trial with a 6-month nutrition/stimulation/hygiene education intervention among mothers of children aged 6–8 months to improve child development and growth. Development was assessed using Bayley Scales of Infant and Toddler Development–III (BSID-III) and Ages and Stages Questionnaire (ASQ), whereas anthropometry was used to assess growth. Urine iodide concentration (UIC) and urine iodide/creatinine ratio (ICR) were measured. SETTING: The current study was conducted in southern Uganda. PARTICIPANTS: We randomly selected 155 children from the 511 enrolled into the original trial and analysed data when they were aged 20–24 and 36 months. RESULTS: Median UIC for both study groups at 20–24 and 36 months were similar (P > 0·05) and within the normal range of 100–199 µg/l (0·79–1·60 µmol/l), whereas the intervention group had significantly higher ICR at 20–24 months. The BSID-III cognitive score was positively associated (P = 0·028) with ICR at 20–24 months in the intervention group. The ASQ gross motor score was negatively associated (P = 0·020) with ICR at 20–24 months among the controls. ICR was not significantly associated with anthropometry in the two study groups at either time-point. CONCLUSIONS: Following the intervention, a positive association was noted between ICR and child’s cognitive score at 20–24 months, whereas no positive association with ICR and growth was detected. Iodine sufficiency may be important for child’s cognitive development in this setting.