碘摄入量增加对甲状腺疾病影响的五年前瞻性流行病学研究

Impact of iodine intake on thyroid diseases——A five-year prospective epidemiological study

目的探讨碘摄入量与甲状腺疾病发生发展的关系。方法于1999年在3个不同的碘摄入量地区,盘山(轻度碘缺乏地区)、彰武(碘超足量地区)、黄骅(碘过量地区),启动对3 761名居民甲状腺疾病的五年前瞻性观察。检查项目包括甲状腺功能、自身抗体和甲状腺B超。2004年随访上述人群,随访率为80．24%。结果(1)1999年初访,彰武和黄骅临床甲状腺功能减退症(甲减)患病率分别是盘山的3．5倍和7．3倍；彰武和黄骅亚临床甲减的患病率分别为盘山的3．2倍和6．6倍；3个地区临床甲减的5年累积发病率差异无统计学意义,但是亚临床甲减的5年累积发病率彰武和黄骅分别为盘山的11．3倍和12．6倍；(2)1999年初访,彰武和黄骅的自身免疫甲状腺炎(AIT)的患病率分别是盘山的3．8倍和6．2倍；彰武和黄骅的AIT的5年累积发病率分别是是盘山的4．4倍和5．5倍；(3)在3个地区甲状腺过氧化物酶抗体阳性、TSH正常者中,5年后甲减的累积发病率彰武和黄骅分别是盘山的4．2倍和10．3倍；(4)3个地区相比临床甲状腺功能亢进症(甲亢)的患病率和发病率差异无统计学意义；(5)黄骅甲状腺癌年平均发病率为19．37/10万,全都为乳头状甲状腺癌。盘山和彰武均未发现甲状腺癌病例。结论碘超足量和碘过量可以诱发和促进甲减和自身免疫甲状腺炎的发生和发展,所以尿碘中位数大于200μg/L是不安全的。尿碘中位数持续为600μg/L的高碘地区的甲状腺癌高发现象值得进一步深入研究。

Objective To evaluate the relationship between iodine intake level and the occurrence and development of thyroid diseases. Methods During the period of 1999-2004, a cross-sectional survey in 1999 and a 5-year follow-up survey were conducted in the 3 communities with different iodine intake levels in China： Panshan （ mild deficiency）, Zhangwu （ more than adequate） and Huanghua （ iodine excess）. A total of 3 761 subjects were included in 1999 and 80.24% of them participated in the 5-year follow-up survey in 2004. The levels of serum thyroid hormones and thyroid autoantibodies were measured, and thyroid B ultrasound was performed. Results （ 1 ） The prevalence of overt hypothyroidism in 1999 in Zhangwu and Huanghua was 3.5 and 7.3 times, and that of subclinical hypothyroidism was 3.2 and 6.6 times as high as in Panshan, respectively. The 5-year cumulative incidence of subclinical hypothyroidism was 11.3 and 12.6 times as high as in Panshan, but no difference of incidence of overt hypothyroidism was found. （2） The prevalence of autoimmune thyroiditis （AIT） in 1999 in Zhangwu and Huanghua was 3.8 and 6.2 times, and the 5-year cumulative incidence of AIT was 4.4 and 5.5 times as high as in Panshan. （3） During the 5-year follow-up period, the incidences of hypothyroidism in subjects with positive thyroid peroxidase antibody and euthyroidism in Zhangwu and Huanghua were 4.2 and 10.3 times as highas in Panshan. （4） No significant differences in both prevalence in 1999 and 5-year cumulative incidence of overt hyperthyroidism were found in the 3 communities. （5） The incidence of thyroid cancer was 19.37/100 000 per year in Huanghua, and all of the cases were papillary thyroid cancer, and no thyroid cancer was found in Zhangwu and Huanghua. Conclusion More than adequate or excessive dietary iodine intake may induce and promote the occurrence and development of hypothyroidism and AIT, therefore, median urinary iodine excretion （MUI） more than 200 μg/L in the population appears not safe. The observation that a higher incidence of thyroid cancer occurred in the iodine excessive areas with MUI 600 μg/L deserves further investigation.