孕期碘摄入量对母子健康影响及不同孕期碘需要量的研究

With the implementation of Universal Salt Iodization, iodine nutrition status for Chinese people has been improved remarkably. However, pregnant women are suffering from both iodine deficiency and iodine excess due to special iodine requirement of pregnancy and wide natural variation in water iodine levels in China. The RNI and UL for pregnancy in China was set by extrapolation from foreign data, as it was lack of actual RNI and UL research for pregnancy. Basing on previous research on iodine UL for adults and epidemiological survey on iodine nutritious status of pregnancy in high iodine areas, on one hand, we will conduct iodine balance study on healthy pregnant women individually, analyzing and deducing RNI for healthy pregnant women. On the other hand, we will carry out a survey on thyroid function of pregnant women with mild iodine deficiency and excessive exposure in high iodine areas at different levels, providing suggestion on iodine supplementation for pregnancy with excessive iodine intake in each stage; safety intake of iodine for pregnancy would be set with this prospective study on the effect of iodine intakes on maternal and infant health. The establishment of EAR and UL, based on synthetically studying the effects of iodine intakes on maternal and infant health from both individual level and population level, will not only provide data foundation to revision of DRIs of iodine in China and prevention of pregnancy hazard caused by iodine deficiency and excess, but also guarantee a scientific and long-term iodized salt supplementation.

全民食盐加碘（USI）实施以来，我国居民碘营养得到显著改善，但由于孕妇对碘的特殊需求以及我国高水碘地区和病区的自然分布，使得我国孕妇正遭受碘缺乏和碘过量的双重危害。目前国内缺乏孕妇碘推荐摄入量（RNI）和可耐受最高摄入量（UL）的基础研究，只能借鉴国外数据。因此，我们在前期成人碘UL研究及高碘地区孕妇碘营养的流行病学调查等工作基础上，一方面拟对健康孕妇在个体水平进行碘平衡研究，分析碘平衡状态与碘摄入量的关系，推导健康孕妇碘的RNI；另一方面拟对不同孕期轻微碘缺乏孕妇和不同高碘暴露的孕妇在人群水平进行随访监测，探讨不同碘摄入量对母体及子代的影响，判定我国孕妇碘的UL。即综合个体和人群两个水平，系统地研究不同碘摄入量对健康孕妇及后代的影响，以明确我国孕妇碘的RNI和UL，为我国人群碘DRIs的修订提供第一手的资料，同时也为孕期碘缺乏和碘过量危害的防治工作及USI持久科学地实施奠定研究基础。

目前中国居民碘DRIs仍缺乏来源于中国孕妇人群的直接数据，基于本课题组前期孕妇工作基础，针对不同碘暴露的孕妇人群开展流行病学研究。此次研究中非高碘地区（碘盐覆盖率92%）孕妇总体尿碘为158 (108-231) μg/L，处于碘适宜范围，但仍有42.6%的孕妇UIC<150μg/L，20.6%的孕妇UIC>250μg/L，尿碘随孕期的增加而降低；分别在非高碘地区和高碘地区进行孕妇碘平衡实验，发现高碘地区孕妇的碘平衡值较非高碘地区高，说明探讨孕妇碘需要量需在碘适宜人群中开展；孕早、中、晚三期孕妇的碘平衡值分别为170μg/d、163μg/d和214μg/d；高水碘地区由于高碘村改水及食用无碘盐，故孕妇总体UIC处于碘适宜，但仍有48.8%的孕妇UIC>250μg/L；当孕妇碘摄入量为250-349μg/d时，TGR最低（<5%）；摄入量为450-500μg/d时，TGR>5%，推荐孕妇碘安全上限值为450μg/d左右，低于成人。非高碘地区孕妇的配偶总体UIC处于碘适宜状态，与孕妇尿碘无差异且呈正相关；采用ICP-MS测定非高碘地区孕妇血清碘，血清碘过低可致孕妇患低甲状腺素血症风险增高；血清碘过高则甲状腺毒症患病风险增高；非高碘与高碘地区产后2年母亲和幼儿碘营养及Gesell评价结果未见差异，随访仍在进行。本研究明确了不同水碘地区孕妇的碘营养情况，明确了不同碘暴露的孕妇碘营养及甲状腺功能的变化情况，也明确了孕期不同碘营养对母子健康的影响，获得直接来源于中国孕妇人群的碘安全摄入范围的数据，为今后进一步完善膳食碘推荐摄入量标准提供科学依据。