To understand the prevalence of thyroid nodules of children lived in different water iodine areas in Cangzhou City.

From Oct. 2015 to Jan. 2017, 15 villages were selected as monitoring sites in Cangzhou, two drinking water samples were collected from each survey site (all had centralized water supply), and the water iodine content was determined. A total of 100 children aged 8 to 10 (half male and female) were examined for thyroid nodules, and at least 50 children (half male and half female) were selected to detect urinary iodine content. In the high iodine water counties, the monitoring sites of iodine salt was according to "National Iodine Deficiency Monitoring Program"; in the monitoring sites of iodine salt supplied counties, students in the monitored village were asked to detect urinary iodine and household salt samples were collected to monitor salt iodine. In the high iodine area, the salt iodine test was carried out by semi-quantitative method. In the non-high iodine area, the salt iodine content of the iodized salt monitoring sites was determined by direct titration, the salt iodine content of Chuan salt and other intensified edible salt was tested by arbitration (GB/T 13025.7-2012). Water iodine and urinary iodine were tested by arsenic and cerium catalytic spectrophotometry.

Water iodine content was 28.2-1 128.0 μg/L in 15 villages; a total of 1 066 urine samples were examined, the median of uriary iodine in each village was 102.6-1 162.0 μg/L; a total of 1 575 children aged 8 to 10 years were examined, among them, 125 cases of thyroid nodules were detected; thyroid nodules detection rate was 7.9%. The prevalence of male was 7.0% (61/871), and the prevalence of female was 9.1% (64/704), there was no significant difference in the detection rate of thyroid nodules between different sex (χ²= 2.07, P > 0.05); The detection rate of thyroid nodules were 4.5% (23/508), 7.8% (4/51), 11.6% (59/507) in children with urinary iodine at the appropriate level (100-< 200 μg/L), the appropriate level (200-< 300 μg/L) and iodine excess level (≥300 μg/L), the difference of thyroid nodules in children with different levels of urinary iodine detection rate was statistically significant (χ²= 17.30, P < 0.01). The difference of prevalence of thyroid nodules in children aged 8 to 10 years with water iodine concentrations of 10-< 100, 100-< 300 and ≥300 μg/L was statistically significant [2.9% (13/448), 7.9% (25/317), 10.7% (87/810), χ²= 23.86, P < 0.05]. The patients with unilateral thyroid nodule accounted for 64.8% (81/125); the patients with multiple thyroid nodules counted for 58.4% (73/125), and 34.2% (13/38), 69.0% (60/87) in areas with iodine content less than 300 μg/L and no less than 300 μg/L, the difference between the two was statistically significant (χ²= 13.14, P < 0.01). A total of 1 800 salt samples were collected from the high water iodine counties, of which 1 779 were iodine-free salt, the rate of iodine-free salt was 98.8%; a total of 190 salt samples were collected in student family, in the 4 iodized salt monitoring sites, the salt iodine median of resident's edible salt was 0.0 mg/kg.

The prevalence of thyroid nodules in children aged 8-10 years may be related to high water iodine in Cangzhou City; children with multiple thyroid nodules is also significantly higher in water iodine content greater than 300 μg/L areas.

Thyroid nodules; Water; Urine; Iodine