酶联荧光分析法测定血清心肌肌钙蛋白I

Determination of cardiac troponin I in serum by enzyme-linked fluorescent assay

目的对酶联荧光分析法(ELFA)检测血清心肌肌钙蛋白I(cTnI)进行方法学评价,并探讨其临床应用价值。方法系统研究ELFA法测定cTnI的精密度、灵敏度、线性范围、回收率、标准曲线的稳定性及干扰因素,并与酶联免疫吸附试验(ELISA)检测结果相比较。同时应用ELFA法测定50名正常人、62例非心肌梗死患者及53例急性心肌梗死(AMI)患者的血清cTnI水平。结果ELFA法检测cTnI的总CV值为2.58%～4.82%,分析灵敏度为0.05μg/L,线性范围0.1～50μg/L,稀释标本的平均回收率为101.2%,标准曲线至少可稳定14d。ELFA法(Y)与ELISA法(X)具有良好的相关性(Y=0.983X-0.148,r=0.996)。加入高浓度的胆红素、三酰甘油和血红蛋白对测定无显著性影响(P>0.05)。AMI患者血清cTnI[(18.6±4.8)μg/L]显著高于正常人[(0.068±0.014)μg/L]和非心肌梗死患者[(0.055±0.021)μg/L](P<0.01);cTnI诊断AMI的阈值为0.8μg/L,诊断敏感度、特异度、准确度分别为91.4%、93.8%、92.9%,阳性和阴性拟然比分别为14.6和0.09。结论ELFA法操作简便、结果准确可靠、自动化程度高,且检测快速,具有较高的精密度;cTnI是敏感、特异的心肌标志蛋白,适合在临床工作中推广应用。

Objective To evaluate the analytical features of the new automated cardiac troponin I(cTnI) assay using enzyme-linked fluorescent assay(ELFA) technology and to obtain information about its utility in clinical studies. Methods The parameters links precision,analytical sensitivity,linearity range,recovery rate,calibration curve stability and interfere factors of the cTnI assay were determined. The comparison study was also performed versus enzyme-linked immunosorbent assay(ELISA). cTnI concentration was determined in 50 healthy individuals,62 patients without acute myocardial infarction(AMI) and 53 patients with AMI by ELFA. Results The total coefficient of variation was from 2.58 % to 4.82%. The minimal detection limit was 0.05μg/L. The linearity range was from 0.1 μg/L to 50μg/L. The mean recovery rate of dilution samples was 101.2%. The calibration curve was stable for at least fourteen days. Linear regression analysis showed a good correlation between the ELFA(Y) and ELISA(X) methods(Y=0.983X-0.148,r=0.996). Adding of high concentration of bilirubin,triglyceride or hemoglobin into samples did not interfere cTnI measurement by proposed method(P>0.05). The statistical difference was much higher in patients with AMI compared with healthy individuals[(18.6±4.8)μg/L vs (0.068±0.014)μg/L,P<0.01] or without AMI[(18.6±4.8)μg/L vs ( 0.055 ±0.021)μg/L,P<0.01]. The cutoff value was 0.8μg/L for laboratory diagnosis of AMI,and sensitivity,specificity,accuracy,positive likelihood ratio and negative likelihood ratio were 91.4%, 93.8 %,92.9%,14.6 and 0.09,respectively. Conclusion The ELFA method is reliable,precise,fairly rapid and easy to perform. cTnI is a sensitive and specific marker of myocardial damage. This method is very useful and suitable for routine determinations of serum cTnI levels in clinical laboratory.