目的

比较评价感染性疾病患儿血清中肌酸激酶同工酶(creatine kinase, CK)-MB活性、CK-MB质量与肌钙蛋白（cardiac troponin I, cTnI）的差别与临床价值。

方法

采用回顾性实验诊断研究。收集2014年1月至12月在第二军医大学附属长征医院和解放军第94医院急诊科、儿科门诊就诊的患感染性疾病患儿1026例 (包括89例临床诊断为病毒性心肌炎患儿) 的入院血清标本1026份；用免疫抑制法检测其CK-MB活性（采用临床正常参考值＜25 U/L和成守金等所采用的较高正常参考值＜46.8 U/L)，用电化学发光技术检测其CK-MB质量和cTnI。同时，采用χ²检验和Wilcoxon带符号秩检验，比较分析在感染性疾病患儿中3项指标间的水平差异和特点。再采集其中422例患儿在第一次采血后的第2至4天后的422份血清标本，并观察3项指标的变化情况。

结果

从1026例患儿中，检出CK-MB活性＞25 U/L或＞46.8 U/L的异常率分别为60.4%(620/1026例)和23.6%(242/1026例)，检出cTnI异常率为9.5%(97/1026例)，2种正常参考值的CK-MB活性异常率高于cTnI异常率(χ²值分别为70.152、328.583, P值均=0.000)；而CK-MB质量检出的异常率为9.2%(94/1026)，但与cTnI的检出异常率的差异无统计学意义(9.5%，χ²=991.068，P>0.05)。其中422例患儿在第一次检测的CK-MB活性和质量及cTnI的四分位值分别为0.05 μg/L、1.82 μg/L、45.0 U/L，第一次检测后2至4 d第2次检测分别为0.05 μg/L、1.82 μg/L、25.5 U/L，首次检测与第2次检测的CK-MB活性和质量值比较，均下降(Z=-17.386，-7.399，P值均=0.000)，但2次cTnI检测值间的差异无统计学意义(Z=-1.219，P=0.223)。

结论

CK-MB质量与cTnI异常的患儿数与临床诊断的病毒性心肌炎患儿例数接近，而CK-MB活性采用2种正常参考值的检测异常率偏高，CK-MB质量可作为未做cTnI检测时的替代辅助诊断感染性疾病患儿心肌炎的指标。同时CK-MB活性和质量随患儿心肌损伤病情的好转，而降低的速度较cTnI更快，因此比cTnI更适合作为评价患儿心肌损伤病情变化或有无新发心肌损伤的敏感指标。

Objective

To compare the application of serum creatine kinase (CK)-MB activity, CK-MB mass and cardiac troponin I(cTnI) in 1026 children who underwent infectiious disease using different cutoff value of CK-MB activity and common cutoff value of CK-MB mass and cTnI. Observe the changing between three indices along with the improving of the infectious disease.

Methods

Retrospective study was used. Serum samples collected from 1026 children with infectious disease were evaluated the CK-MB activity (cut off<25 U/L and 46.8 U/L used by Cheng Soujin), CK-MB mass and cTnI using immunoinhibition method, electrical chemiluminescence immunoassayand automatic chemiluminescence immunoassay,respectively. Chi-square test and Wilcoxon signed rank test were used to compare the abnormal rate of these laboratory indexes in children with infectious diseases. Furthermore,Four hundred and twenty-two in 1026 children were collected after administration(2-4 days) to observe the change of these laboratory indexes.

Results

The abnormal rates of CK-MB activity were 60.4% (＞25 U/L，620/1026) , 23.6% (＞46.8 U/L，242/1026)，respectively. The abnormal rates of CK-MB mass and cTnI were 9.2% (94/1026) and 9.5%(97/1026). A statistically significant difference was found in the abnormal rate of CK-MB activity（using two different cutoff values）and cTnI(χ²=70.152, 328.583, P=0.000),but there were no significance of CK-MB mass and cTnI using common cutoff value（χ²=991.068,P=0.25). Four hundred and twenty-two children were reinspected serum CK-MB activity, CK-MB mass and cTnI in 2-4 days after the first tests. The level of CK-MB activity and CK-MB Mass were dropped significantly(Z=-17.386，-7.399，P=0.000), but the level of cTnI was not severely down(Z=-1.219，P=0.223).

Conclusions

The number of patients with abnormal CK-MB and cTnI is close to the clinical diagnosis of viral myocarditis, but the abnormal rate of CK-MB activity is higher than cTnI. And CK-MB mass could be used as an alternative for cTnI testing when the diagnosis of infectious diseases in children with myocarditis indicators.Meanwhile, CK-MB activity and CK-MB mass dropped faster than cTnI when myocardial injury improvement of patients. Therefore, CK-MB activity and CK-MB mass are more suitable than cTnI as a sensitive index for evaluating the changes of myocardial injury or new presence of myocardial injury in children.