小儿体外循环心脏手术对甲状腺激素代谢的影响

目的观察低体重婴幼儿体外循环心脏手术前后甲状腺激素的变化，探讨其对甲状腺激素代谢的影响。方法选择21例10kg以下婴幼儿行体外循环心脏手术。分别于体外循环前、体外循环结束时、术后第一天、第二天和第四天采取其静脉血样，观察其血清的三碘甲状腺原氨酸（T3）、甲状腺素（T4）和促甲状腺激素（TsH）浓度变化。结果T3浓度在体外循环后明显下降（P〈0．05），术后第二天降至最低，至术后第四天仍未恢复至体外循环前水平；T4在体外循环结束时及术后第一天轻度下降，第二天明显下降（P〈0．05），第四天恢复至体外循环前水平；TSH于体外循环时轻度升高。术后第一天和第二天明显下降（P〈0．05），第四天升高超过体外循环前水平。结论10kg以下婴幼儿在体外循环心脏手术囤术期不同时期可以发生甲状腺功能正常的病态综合征，表现为T3、T4和TSH的下降，这表明体外循环心脏手术对低体重婴幼儿甲状腺激素代谢有重要影响，因此加强围术期患儿甲状腺激素的监测及术后尽早补充甲状腺激素对患儿恢复有重要作用。

EFFECTS OF CARDIOPULMONARY BYPASS OF CARDIAC SURGERY ON THYROID HORMONE IN LOW WEIGHT INFANTS

Objective To observe the tendency and change of thyroid hormone perioperatively, and explore the effects of CPB on thyroid hormone metabolism in low weight infants undergoing CPB cardiac surgery. Methods 21 infants weighting less than 10 Kg undergoing ventricular septal defect（VSD） repair surgeries on CPB was investigated. The venous blood samples were collected at five time points： before CPB, after CPB, 1 day, 2 day, and 4 day postoperatively. The concentration serum thyroid hormone triiodothyronine （ T 3 ）, tetraiodothyronine （ T4 ） and thyroid stimulating hormone （ TSH ） were assayed by microparticle enzyme immunoassay （MEIA）. Results The concentration of T3 decreased significantly after CPB and the second day postoperatively reached the lowest point. Then it began to recovery, but didn＇t reach the level before CPB on the fourth day yet. The concentration of T 4 didn＇t decrease obviously after CPB and the first day postoperatively, while it decreased on the second day and recoverd to the level before CPB on the fourth day. The concentration of TSH increased rather than decreased after CPB, while decreased obviously on the first and second day after operation. Then it recovered to the level before CPB on the fourth day. Conclusion CPB cardiac surgery in infants is a definite risk factor related to euthyroid sick syndrome, especially for low birth weight infants. In- fants weighting less than 10Kg undergoing CPB surgeories could develop type 1I euthyroid sick syndrome perioperatively and the concentrations of T3, T4 and TSH decreases at different time points. CPB cardiac surgery has great effects on the level and function of thyroid hormone of infants, especially for low birth weight infants. So it makes great sense to monitor the thyroid hormone level of the infants perioperatively and supplement thyroid hormone early after cardiac surgery.