早孕期甲状腺过氧化物酶抗体阳性对甲状腺功能的影响

目的：探讨妊娠8~12周甲状腺过氧化物酶抗体(TPOAb)阳性对甲状腺功能的影响。方法：对2010年9月至2011年6月北京友谊医院产科门诊行产前检查的611例无甲状腺疾病高危因素的健康初产妇，于妊娠8~12周进行甲状腺功能促甲状腺激素(TSH)、游离四碘甲状腺原氨酸(FT4)]和TPOAb的检测，通过制定早孕期甲状腺功能正常参考区间，分析TPOAb阳性切割值、阳性率及对TSH、FT4的影响。结果：(1)妊娠8~12周TPOAb中位数值及变化范围为38.9(6.4~>1300)mU/L。(2)通过建立妊娠8~12周人群特异参考标准，以第90百分位计算TPOAb阳性切割值为206.77 mU/L，TPOAb阳性率为10.8%(66/611)。(3)回归分析显示：TPOAb滴度与TSH呈正相关，与FT4呈负相关，P值均为0.000。妊娠8~12周TPOAb阳性妇女TSH中位数值较TPOAb阴性者升高0.4 mU/L，前者TSH异常升高的风险是后者的4.4倍。结论：妊娠8~12周TPOAb阳性率为10.8%，通过建立妊娠期人群特异甲状腺功能参考标准和TPOAb阳性切割值，可避免过高估计TPOAb的阳性率。TPOAb阳性孕妇发生TSH异常升高的风险明显增加。

An analysis of maternal thyroid peroxidase autoantibody positivity in the first trimester

Objective：To assess the prevalence of thyroid peroxidase autoantibody and relationships between thyroid function and TPOAb in the first trimester of pregnancy. Methods：A total of 611 women during the first trimester from Beijing Friendship Hospital are tested for serum TSH，FT4 and anti-TPO by chemilumino metric immunoanalysis . Women with previous thyroid diseases are excluded. We determine the reference intervals for TSH and FT4 and establish the prevalence of TPOAb by using gestational age-specific interval. The relationships between TSH，FT4 and TPOAb are analyzed. Results：(1)The median value of TPOAb is 38.9 mU/L，ranging from 6.4 to more than1 300 mU/L at 8-12 gestational week .(2)The cutoff value of TPOAb is 206.77 mU/L at the 90th percentile by using gestational age-specific interval. The positive rate of TPOAb is 10.8% (66/611).(3)A simple regression analysis shows that serum titer of TPOAb correlates with the levels of TSH and FT4 (P= 0.000 and 0.000). The median concentration of TSH is significantly greater in TPOAb positive women than in TPOAb negative women with increased value of 0.40 mU/L. The risk of abnormally high TSH in former is more than three times than in latter. Conclusion：TPOAb positive rate is 10.8% in first trimester. Determination of the gestational age specific intervals for TSH，FT4 and TPOAb is of very importance to avoid overestimation of maternal thyroid dysfunction. Pregnant women with TPOAb positive have a higher level of TSH and should be monitored closely for thyroid function. 