不同含量水碘对特殊人群碘营养、甲状腺功能和容积的影响

Effects of different iodine concentration in drinking water on iodine nutrition, thyroid function and volume

目的 调查水源性高碘地区儿童和妇女的碘营养状况及当地人群甲状腺容积和功能状态,探讨高碘地区划定的水碘界值问题.方法 在太原市小店区、清徐县的高碘乡镇,将所辖村按水碘含量50～＜100、100～＜150、150～＜300、≥300 μg/L划分为4组,分别为A、B、C、D组,每组选择2～3个村作为调查点.每组抽取200名8～10岁学龄儿童和60名妇女（包括孕妇、哺乳期妇女、育龄妇女各20名）作为调查对象.采集各调查对象家庭饮用水、食用盐和一次尿样,分别检测水碘、盐碘和尿碘.同时检测8～ 10岁儿童甲状腺容积.在知情同意情况下,采集妇女血样,检测游离三碘甲腺原氨酸（FT3）、游离甲状腺素（FT4）、促甲状腺激素（TSH）.结果 选择家中食用无碘盐的708名儿童和236名妇女作为调查对象.A、B、C、D组儿童饮用水水碘分别为73.8、144.7、258.5 501.0 μg/L,4组妇女饮用水水碘分别为73.8、144.7、242.7、485.9 μg/L.A、B、C、D组儿童尿碘分别为274.3、312.8、455.6、793.5 μg/L,4组妇女尿碘分别为238.3、235.2、371.6、641.6μg/L.儿童和妇女尿碘水平均随水碘值的升高而升高.A、B、C、D组儿童甲状腺肿大率分别为5.6％（11/196）、13.2％（25/189）、12.6％（20/158）、10.9％（18/165）,甲状腺肿大率随着水碘水平升高而增高.在A、C、D组,孕妇FT3、FT4水平[pmol/L：（3.70±0.59）,（14.01±2.44）;（3.43±0.57）,（12.87±2.12）;（3.42±0.47）,（12.66±1.78）]均低于哺乳期妇女[pmol/L：（4.26±0.57）,（14.73±2.36）;（4.28±0.40）,（14.77±1.19）;（4.36±0.65）,（15.66±2.84）]、育龄妇女[pmol/L：（4.80±0.50）,（17.47±2.11）;（4.21±0.48）,（15.83±1.64）;（4.26±0.52）,（15.53±1.81）],且随着各组调查点水碘水平的逐步升高,妇女的FT4激素水平逐渐下降,TSH水平逐渐上升.结论 水碘含量超过100 μg/L后,儿童甲状腺肿大率明显升高,儿童和妇女碘营养水平随水碘含量升高相继出现过量.妇女亚临床甲状腺功能减退症的发病危险性随水碘含量升高而增加,在水碘含量超过300μg/L,亚临床甲状腺功能减退症明显增高.建议将高碘地区划定标准的水碘含量切点值由150μg/L下调至100μg/L.

Objective Toinvestigate iodine nutrition,thyroid volume and function of children and women in high water iodine areas,and to discuss the cut-off point of water iodine level where should be defined as iodine excessive areas.Methods In iodine excessive townships in Xiaodian and Qingxu Counties of Taiyuan City,all villages were divided to 4 groups according to the concentration of iodine in drinking water：50 ～ 〈 100 μg/L （Group A）,100 ～ 〈 150 μg/L（Group B）,150 ～ 〈 300 μg/L（Group C） and ≥300 μg/L（Group D）,and 2-3 villages were randomly selected from each group as investigation sites.Two hundred children aged 8-10 and 60 women （20 pregnant women,20 breasffeeding women and 20 women of childbearing age,respectively） were sampled.Drinking water,edible salt and once random urine samples for each studying object were collected,and the iodine content was measured.The goiter volume of children aged 8-10 and triiodothyronine （FT3）,free thyroxine （FT4）,thyroid stimulating hormone （TSH） of women were determined.Results Totally 708 children and 236 women were selected as respondents who ate non-iodized salt.Iodine content in drinking water of children in groups A,B,C and D was 73.8,144.7,258.5 and 501.0 μg/L,respectively,and that of women was 73.8,144.7,242.7 and 485.9 μg/L,respectively.Median urinary iodine of children in groups A,B,C and D was 274.3,312.8,455.6 and 793.5 μg/L,respectively,and that of women was 238.3,235.2,371.6 and 641.6 μg/L,respectively.The median urinary iodine of children and women increased with increasing water content of iodine.The goiter rate of children was 5.6% （11/196）,13.2% （25/189）,12.6% （20/158） and 10.9% （18/165） for each group,respectively,which also increased with increasing water content of iodine.In groups A,C and D,the FT3 and FT4 levels[pmol/L：（3.70 ± 0.59）,（14.01 ± 2.44）; （3.43 ± 0.57）,（12.87 ± 2.12）; （3.42 ± 0.47）,（12.66 ±1.78）] in pregnant woman were lower than those in breasffeeding women[pmol/L：（4.26 ± ±0.57）,（14.73 ± 2.36;（4.28 ± 0.40）,（14.77 ± 1.19）; （4.36 ± 0.65）,（15.66 ± 2.84）] and women of childbearing age[pmol/L：（4.80 ±0.50）,（17.47 ± 2.11）; （4.21 ± 0.48）,（15.83 ± 1.64）; （4.26 ± 0.52）,（15.53 ± 1.81）].With increasing water content of iodine,FT4 level was decreasing and TSH level was increasing gradually in women.Conclusions When water iodine exceeds 100 μg/L,goiter rate of children has increased significantly.Iodine excessive women and children have appeared one after another with increasing water content of iodine.Women incidence of subclinical hypothyroidism risk has increased with increasing water content of iodine,and the detection rate of subclinical hypothyroidism is significantly higher when water iodine is higher than 300 μg/L.The cut-off point of iodine excessive areas should be descend from 150 μg/L to 100 μg/L.