A Prospective Study on the Changes of Serum 3,5,3'-Triiodothyronine Levels after Cardiopulmonary bypass in Pediatric Age

소아환자에서 개심술후 혈중 3,5,3'- 삼옥소타이로닌 [triiodothyronine] 농도 변화에 관한 연구

Triiodothyronine[T3] is an important regulator of the tissue metabolism, and may have potential use as an inotropic agent. The change of serum T3 level was studied in the pediatric age patients after cardiopulmonary by pass. Thyroid function was tested pre-operatively in 33 patients and total triiodothyronine[TT3] levels were serially measured during and after cardiopulmonary bypass[CPB]. After correction of dilutional effect, effects of various factors on the TT3 levels were analyzed. Abrupt fall of TT3 level was demonstrated at 15 minutes after CPB[80.1$\pm$5.9ng/dL] from the initial level of 133.6$\pm$5.3ng/dL, with some recovery at 6 hours[115.4$\pm$6.7ng/dL]. After then, gradual decrease occured reaching to the level of 77.2$\pm$4.2ng /dL at 24 hours. These falls of the TT3 after CPB were statistically significant. [p<0.01 ANOVA] Statistically significant correlation were found between the degree of hemodilution and TT3 concentration at 15 and 30 minutes after CPB[p<0.05]. But, other factors were analyzed to have no effect on TT3 levels. As the degree of the hemodilution increases, TT3 decreased less. This observation probably supports the fact that decrease of TT3 during CPB may be a result of sequestration of T3 into peripheral tissue. Although it was not statistically significant[p=0.08], the fall of TT3 was greater in the group to which plasmanate was added, than those not added. This finding seemed to be due to the increase of albumin and other thyroid-hormone-binding-proteins in the serum. Increase of these binding proteins might potentiate the sequestration of T3 into the liver and the kidney from serum, and as a consequence, decrese the serum TT3 level further.