全民食盐加碘后碘缺乏病变化特征与影响因素

Impact of adoption of iodine salt on the incidence of iodine deficiency disease in Chongqing

目的探索全民食盐加碘后重庆市碘缺乏病变化特点和影响因素。方法 1997-2009年,抽样检测居民户盐碘含量,计算碘盐覆盖率和合格碘盐食用率;用触诊法和B超法同时检查8～10岁儿童甲状腺容积,计算肿大率和容积均数、中位数、众数和90、95、99的百分位数(P90、P95、P99);检测儿童尿碘,计算中位数和频率。结果碘盐覆盖率和合格碘盐食用率由1997年的89.1%和83.0%显著上升至2009年的98.9%和95.6%(P<0.05);8～10岁儿童甲状腺肿大率触诊法和B超法由1997年的18.3%和17.4%显著降至2009年的7.0%和6.6%(P<0.01);甲状腺容积均数、中位数、众数和P90、P95、P991997年分别为4.32、4.00、3.69、6.30、7.24、8.76ml,2005年分别降至3.66、3.50、3.10、5.00、6.00、6.90ml,2009年均数、中位数、众数分别上升至3.68、3.53、3.37ml,P90、P95、P99分别降至4.79、5.37、6.40ml;儿童尿碘中位数1997-2009年全市性抽样调查为211.9～328.0μg/L,>300μg/L者占1/3以上;2009年儿童尿碘中位数为140～、200～、250～、300～μg/L的区县分别有10、12、11和7个,甲状腺容积均数、中位数、众数和P90、P95随着尿碘升高而增大;经济收入为2000～、3000～、4000～元的区县儿童甲状腺容积各项指标随收入增加而降低。结论随着碘盐覆盖率和合格碘盐食用率的提高,重庆市人群碘营养水平充足,儿童甲状腺肿大率不断下降。但存在碘过量现象,碘过量和经济收入是儿童甲状腺肿的影响因素,应降低食盐加碘浓度。儿童甲状腺容积有总体增大趋势,有必要重新制定儿童甲状腺容积正常值新标准。

Objective To study the impact of adoption of iodine salt on the incidence of iodine deficiency disease. Methods Iodine content in salt samples collected between 1997 and 2009 was determined. The coverage of iodized salt usage and the rate of qualified iodine salt were calculated. Thyroid volume of children between 8 to 10 years old was evaluated by palpation and B ultrasound method. Goiter rate, median, mean, mode, P90, P95 and P99 of thyroid volume were calculated. The level of urinary iodine was also measured. Results Iodized salt coverage rate was increased from 89.1% in 1997 to 98.9% in 2009（P0.05）,and the rate of qualified iodized salt was increased from 83.0% in 1997 to 95.6% in 2009（P0.05）.For the children between 8 to 10 years old, the goiter rate was decreased from 18.3% in 1997 to 7.0% in 2009 by palpation method （P0.05）, and decreased from 17.4% in 1997 to 6.9% in 2009 by B ultrasound method （P0.05）. The mean value, median, mode, P90, P95 and P99 of thyroid volume was decreased from 4.32, 4.00, 3.69, 6.30, 7.24 and 8.76 ml in 1997 to 3.66, 3.50, 3.10, 5.00, 6.00 and 6.90 ml in 2005, respectively. Whereas, the mean, median and mode of thyroid volume was increased to 3.68, 3.53 and 3.37 ml in 2009, but the P90,P95 and P99 of the thyroid volume was decreased to 4.79, 5.37 and 6.40 ml in 2009. The median children urinary iodine content was 211.9-328.0 μg/L between 2007 to 2009. 1/3 of the samples had the concentration higher than 300 μg/L. The median urinary iodine content from children living in county district was 140-250 ml between 1997 to 2009. The median, mean, mode, P90 and P95 of thyroid volume were increased by increasing urinary iodine, which were decreased by increasing resident＇s income where the income were 2 000-4 000 RMB in county district. Conclusion Iodine contents are sufficient and the incidence of goiter in children was decreasing in Chongqing after increasing the coverage of iodized salt. Iodine in residents was excessive. Iodine excessive and resident＇s income are influence factors to goiter rate of children. The content of iodine in salt should be reduced. It is necessary to developing a new standard of thyroid volume for children.