盐碘浓度下调后武威市儿童碘营养及甲状腺功能状况调查

Investigation on iodine nutrition and thyroid function of children in Wuwei City after salt iodine concentration decreased

目的了解盐碘浓度下调后儿童的碘营养水平和甲状腺功能状况,为精准化补碘提供理论依据。方法选择甘肃省经济水平中等、水碘含量<10μg/L、碘盐措施到位的武威市8~10岁儿童为研究对象。采集样本人群晨起空腹血样及任意一次尿样,检测甲状腺激素及尿碘水平;采用分层抽样法采集居民户盐样,测定盐碘含量。结果(1)盐碘浓度下调后,居民户合格碘盐食用率仍在90%以上,盐碘中位数由31.0 mg/kg降至26.9 mg/kg。(2)盐碘浓度下调后,儿童尿碘中位数由290.84μg/L降至187.37μg/L,差异有统计学意义(P<0.05)。尿碘在100~200μg/L的比例从15.63%升高至44.44%,尿碘>300μg/L的比例由46.88%降至17.39%,差异均有统计学意义(P<0.05)。(3)盐碘浓度下调后,儿童血清TSH水平由3.84 mIU/L降至3.32 mIU/L,血清FT3水平由5.84 pmol/L升至5.91 pmol/L,血清FT4水平由17.47 pmol/L降至16.79 pmol/L,其中TSH和FT4前后比较差异有统计学意义(P<0.05)。(4)盐碘浓度下调前后,儿童甲状腺功能总体异常率分别为9.38%和9.66%,差异无统计学意义。亚甲减发生率由7.29%降至2.89%,低T4血症由0%升至3.86%,差异均有统计学意义(χ^(2)=4.038,P=0.044;P<0.05)。(5)盐碘浓度下调后,儿童TgAb阳性率由2.61%升高至7.25%,差异有统计学意义(χ^(2)=4.459,P=0.035);TMAb阳性率由4.69%升高至6.76%,差异无统计学意义。结论盐碘浓度下调后,武威市儿童碘营养状况由超适宜降至适宜水平,适宜范围内的儿童比例明显升高;血清TSH水平、FT4水平和亚甲减发生率显著降低,这一改变可能降低儿童罹患甲状腺疾病的风险。

Objective To understand the iodine nutrition and thyroid function of children after the reduction of iodine concentration in salt,so as to provide theoretical basis for precise iodine supplement.Methods In 2009 and 2015 before and after the reduction of iodine concentration in salt,the 8-10-year-old children in Wuwei City with middle economic level,water iodine content<10μg/L and iodized salt measures in place were selected as the research objects.The fasting blood samples and any urine samples were collected from the sample population in the morning to detect the thyroid hormone and urinary iodine levels,and the salt samples of residents were collected by stratified sampling method to determine the salt iodine content.Results(1)After the reduction of salt iodine concentration in salt,the consumption rate of qualified iodized salt was still over 90%,and the median of salt iodine decreased from 31.0 mg/kg to 26.9 mg/kg.(2)After the reduction of iodine concentration in salt,the median urinary iodine of children decreased from 290.84μg/L to 187.37μg/L,the difference was statistically significant(P<0.05).The proportion of urinary iodine in 100~200μg/L increased from 15.63%to 44.44%,and the proportion of urinary iodine more than 300μg/L decreased from 46.88%to 17.39%,the difference was statistically significant(P<0.05).(3)After the reduction of iodine concentration in salt,the serum TSH decreased from 3.84 mIU/L to 3.32 mIU/L,the serum FT3 increased from 5.84 pmol/L to 5.91 pmol/L,the serum FT4 decreased from 17.47 pmol/L to 16.79 pmol/L,and the difference between TSH and FT4 was statistically significant(P<0.05).(4)Before and after the decrease of salt iodine concentration,the abnormal rate of thyroid function in children was 9.38%and 9.66%,there was no significant difference;the incidence of hypothyroidism decreased from 7.29%to 2.89%,the difference was statistically significant(χ^(2)=4.038,P=0.044,P<0.05).(5)The positive rate of TgAb increased from 2.61%to 7.25%after the decrease of salt iodine concentration,the difference was statistically significant(χ^(2)=4.459,P=0.035);the positive rate of TMAb increased from 4.69%to 6.76%,there was no significant difference.Conclusion After the reduction of salt iodine concentration,the iodine nutritional status of children in Wuwei City decreased from super suitable to appropriate level,and the proportion of children within the appropriate range increased significantly;the level of TSH and FT4 decreased,and the incidence of hypothyroidism decreased significantly,this change may reduce the risk of thyroid disease in children in Wuwei City.