An epidemiological survey of children's iodine nutrition and goitre status in regions with mildly excessive iodine in drinking water in Hebei Province, China

Objective: To identify children's iodine nutrition and goitre status in areas with mildly excessive iodine in drinking water. Design: A cross-sectional survey. Probability proportional to size sampling was employed to randomly select children from thirty townships where the median iodine content in drinking water ranged from 150 to 300 mu g/l; their urinary iodine concentrations were determined and their thyroid volumes were measured by ultrasound. Drinking water samples and salt samples from the villages where the children lived were collected using a systematic sampling method. Setting: Hebei Province of China. Subjects: A total of 1259 children aged 8-10 years (621 boys and 638 girls). Results: Children's median urinary iodine concentration was found to be 418.8 mu g/l, and the iodine concentration was >300 mu g/l for 68.3% (248/363) of the urine samples. Children's median urinary iodine concentration in villages with median salt iodine >10 mg/kg was significantly higher than that in villages with median salt iodine <5 mg/kg (442.9 mu g/l v. 305.4 mu g/l, P approximate to 0). The goitre rate of 1259 children examined by ultrasound was 10.96%. Conclusions: The iodine intake of children living in areas with mildly excessive iodine in drinking water in Hebei Province was found to be excessive. The measured iodine excess in the sampled children is exacerbated by consumption of iodized salt. Goitre was identified in these areas; however, due to the limitation of the current criteria for children's thyroid volume, a comprehensive assessment of the prevalence of goitre in these regions could not be made and further study is required.