Negative interference of bilirubin and hemoglobin in the MEIA troponin I assay but not in the MEIA CK-MB assay

Troponin I is a sensitive and specific marker for the diagnosis of myocardial infarction. Several commercially available immunoassays measure the concentration of troponin I in serum. The microparticle enzyme immunoassay (MEIA) for troponin I (Abbott Laboratories, Abbott Park, IL) is widely used in clinical laboratories, including our hospital laboratory. We studied the effect of bilirubin and hemolysis on the MEIA for troponin I and compared our assay with a newly available chemiluminescent assay (CLIA) for troponin I (Bayer Diagnostics, Tarrytown, NY). We also measured CK-MB concentration using the MEIA CK-MB assay. One serum pool was prepared by combining several specimens of one patient with elevated troponin I and with a diagnosis of myocardial infarction. Other serum pools were prepared by combining sera with similar troponin I values. All serum pools showed normal bilirubin concentrations and had no hemolysis. Then we supplemented aliquots of serum pools with various concentrations of bilirubin (5.0, 10.0, 15.0, and 20.0 mg/dL). After supplementation, troponin I concentrations were measured again using the MEIA and CLIA. We observed a statistically significant decrease in troponin I concentration in the presence of bilirubin with the MEIA. For example, in serum pool 1, the troponin I concentration was 16.3 (bilirubin: 0.8 mg/dL). In the presence of 5.0, 10.0, 15.0 and 20.0 mg/dL of added bilirubin, the cardiac troponin I concentrations were 13.9, 13.4, 13.3 and 13.0 ng/ml respectively. We observed similar negative interference of bilirubin in troponin I measurement by the MEIA in other pools. The troponin I value decreased slightly (not statistically significant) in one pool and did not change in two other pools in the presence of bilirubin when we measured troponin I concentration using the CLIA. Interestingly, bilirubin did not interfere with the MEIA CK-MB assay. Moderate hemolysis did not have any effect on the troponin I assay using either the MEIA or CLIA. However, gross hemolysis (hemoglobin > 40 mg/dL) interfered with both assays for troponin I.     

Improved assay of cardiac troponin I is more sensitive than other assays of necrosis markers

OBJECTIVE: Highly sensitive and specific assays of cardiac troponins I and T are the preferred biomarkers in diagnosing myocardial infarction (MI). Assays of cardiac troponin I (cTnI) have been improved with the addition of antibodies against the cTnI molecule and may have increased sensitivity. We hypothesized that a cTnI assay with modern antibody configuration will exhibit equal or better sensitivity in the setting of acute MI compared to cTnT and other markers of myocardial necrosis. MATERIAL AND METHODS: We investigated release kinetics of cTnI (Abbott ADV, Abbott Diagnostics), cTnT (Roche Diagnostics), CKMBmass, myoglobin and heart fatty acid binding protein (H-FABP) in 23 patients admitted with acute ST-segment elevation MI undergoing primary percutaneous coronary intervention. Calibrators for the Abbott ADV cTnI assay are traceable to the United States National Institute of Standards and Technology (NIST) reference material for cTnI. Eleven blood samples were drawn from each patient in the period from admission to 24 h. Biomarkers of necrosis showed marked increases in relative concentrations, especially within the first 2 h after admission. RESULTS: From 30 min after admission onwards, cTnI exhibited significantly higher relative concentrations compared to cTnT, CKMBmass, Myoglobin and H-FABP (p<0.05). CONCLUSIONS: The NIST standardized Abbott TnI ADV assay appears to be more sensitive than cTnT and other biomarkers in the early phase of MI.     

Cardiac markers: point of care testing.

Point-of-care (POC) or "near-patient" testing allows diagnostic assays to be performed in locations such as the emergency department or intensive care unit where treatment decisions are made and care is delivered based on the results of these assays. Presently, there exist POC immunoassays for several cardiac markers including creatine kinase MB (CK-MB), myoglobin, troponin I, and troponin T that yield qualitative and quantitative results comparable to traditional central lab assays. In the evaluation of emergency room patients with chest pain, POC cardiac markers may improve triage and clinical outcomes. Existing POC assays combining myoglobin and CK-MB have high sensitivity and specificity for diagnosing acute myocardial infarction and may provide the earliest identification of myocardial injury. POC Troponin T assays are the most studied POC cardiac marker assays. Along with POC troponin I assays, these tests provide more sensitive identification of myocardial injury and valuable prognostic information. Prior studies of POC cardiac marker assays have not addressed whether POC testing affects patient outcome or process of care. In situations in which caregivers base triage, treatment and monitoring decisions on time-sensitive diagnostic results, POC tests linked with improved triage and treatment strategies may improve resource utilization and clinical outcomes.     

心肌标志物作用的系统分析

目的：获取心肌生化标记物的最佳应用证据。方法：查循、浏览对心肌肌酸激酶同工酶MB（CK－MB）、肌红蛋白、心肌肌钙蛋白T（cTnT）和心肌肌钙蛋白I（cTnI）用于诊断心肌梗塞（MI）和对急性冠状动脉综合症分级的系统评价和Meta－分析的文献资料。结果：在症状发生后的12－48小时采样分析CK－MB质量对于诊断MI的临床灵敏度和牧场划性分别是98．8％和89．6％。肌红蛋白有高的阴性预示值,在症状发生后的2－6小时采样分析有高的临床灵敏度。在症状发生后的12采样cTnI,诊断MI的临床灵敏度和特异性分别是98．2％和68．8％,其临床特异性降低与检测到微小心肌受损有关。结论：cTnT和cTnI比CK－MB对诊断心肌梗死和预测急性冠状动脉综合症危险性更有价值。     

Improved assay of cardiac troponin I is more sensitive than other assays of necrosis markers

Objective. Highly sensitive and specific assays of cardiac troponins I and T are the preferred biomarkers in diagnosing myocardial infarction (MI). Assays of cardiac troponin I (cTnI) have been improved with the addition of antibodies against the cTnI molecule and may have increased sensitivity. We hypothesized that a cTnI assay with modern antibody configuration will exhibit equal or better sensitivity in the setting of acute MI compared to cTnT and other markers of myocardial necrosis. Material and methods. We investigated release kinetics of cTnI (Abbott ADV, Abbott Diagnostics), cTnT (Roche Diagnostics), CKMBmass, myoglobin and heart fatty acid binding protein (H‐FABP) in 23 patients admitted with acute ST‐segment elevation MI undergoing primary percutaneous coronary intervention. Calibrators for the Abbott ADV cTnI assay are traceable to the United States National Institute of Standards and Technology (NIST) reference material for cTnI. Eleven blood samples were drawn from each patient in the period from admission to 24?h. Biomarkers of necrosis showed marked increases in relative concentrations, especially within the first 2?h after admission. Results. From 30?min after admission onwards, cTnI exhibited significantly higher relative concentrations compared to cTnT, CKMBmass, Myoglobin and H‐FABP (p<0.05). Conclusions. The NIST standardized Abbott TnI ADV assay appears to be more sensitive than cTnT and other biomarkers in the early phase of MI.     

Validation of NACB and IFCC guidelines for the use of cardiac markers for early diagnosis and risk assessment in patients with acute coronary syndromes

BACKGROUND: International guidelines have been established for the use of cardiac markers in the early diagnosis and risk assessment of patients with acute coronary syndromes. METHODS: A single center, prospective observational study was conducted in a tertiary care university hospital on 200 consecutive patients with suspected acute myocardial infarction (AMI). Blood was drawn on admission and after 2, 4, 8, 12 and 24 h for the measurement of CK-MB/CK activity, myoglobin, CK-MB mass and troponin I. A 6-week follow-up was undertaken for the combined end point of acute coronary syndrome and death. RESULTS: Myoglobin showed an early diagnostic sensitivity of 0.65 on admission, 0.90 after 2 h and 0.92 after 4 h compared with 0.46, 0.74 and 0.88 for CK-MB/CK activity. The combination of myoglobin and cTnI increased the diagnostic value compared with myoglobin alone on admission, 2 and 4 h later. In multivariate analysis, cTnI and CK-MB/CK mass, but not myoglobin and CK-MB/CK activity, were shown to be independent predictors on the 6-week follow-up. CONCLUSIONS: Repetitive myoglobin measurements within 4 h of admission, combined with at least one early troponin test, was shown to be the strategy of choice in early AMI diagnosis and prognosis assessment.     

Myoglobin,creatine kinase MB isoforms and creatine kinase MB mass in early diagnosis of myocardial infarction in patients with acute chest pain

OBJECTIVES: Measurements of myoglobin and creatine kinase (CK)-MB isoforms have been suggested to be sensitive tests for the early diagnosis of myocardial infarction (MI). We have investigated the utility of myoglobin, creatine kinase (CK)-MB isoforms and creatine kinase MB mass (CK-MBm) in early diagnosis of MI using cardiac troponin T (cTnT) positivity as a reference. DESIGN AND METHODS: The study population comprised 440 patients who had had chest pain for less than 12 h. Patients were divided into cTnT negative (cTnT-) or cTnT positive (cTnT+) patients (concentration of cTnT >0.1 microg/L at two different time points during 72 h). RESULTS: At the time of admission to the emergency department receiver operating characteristics (ROC) curves of CK-MB isoforms and CK-MBm were not better than that of myoglobin. Six hours after admission CK-MB isoforms and CK-MBm provided statistically significantly larger areas under the curve (AUC) than myoglobin (p < 0.01). When ROC curves were related to the onset of chest pain (< 3 h, 3-6 h, and > 6 h) there were no significant differences between the cardiac markers studied. CONCLUSIONS: According to the present findings, CK-MB isoforms or myoglobin offer no advantage over CK-MBm as early markers of myocardial infarction.     

Effect of elevated concentration of alkaline phosphatase on cardiac troponin I assays.

Troponin I is the regulatory subunit of troponin complex associated with the actin thin filament within muscle cells. Cardiac troponin I (cTnI) is a good marker for diagnosis of myocardial damage. Several immunoassays are available for determination of cTnI in serum. The Stratus cTnI fluorometric enzyme immunoassay (Dade International) uses alkaline phosphatase (ALP) substrate. The microparticle enzyme immunoassay (MEIA) for cTnI (Abbott Laboratories) also uses ALP conjugate. On the other hand, the chemiluminescent assay (CLIA) for cTnI (Bayer Diagnostics) does not use ALP. ALP activity may frequently be elevated in serum of patients being evaluated for suspected myocardial infarction. Therefore, we studied the potential interference of ALP in cTnI assays. Serum pools were prepared from patients, and various concentrations of ALP solution were added to different aliquots. The cTnI concentrations were measured by the Stratus, MEIA, and CLIA assays. We observed no interference of ALP in the MEIA and CLIA assay for cTnI. On the other hand, we observed significant positive interference of ALP when cTnI concentrations were measured using the Stratus.     

Time-dependent diagnostic performance of a rapid troponin T version 2 bedside test in patients with acute coronary syndromes

In a prospective trial, the diagnostic performance of the second version of the troponin T rapid assay (Trop T; cutoff 0.2 microg/L) was compared with the quantitative cardiac-specific troponin T assay (cTnT ELISA; cutoff 0.1 microg/L) and other established cardiac markers such as CK, CK-MB activity, CK-MB mass and myoglobin. Additionally, a 30-day follow-up was performed to determine the suitability of the Trop T assay and the reference markers for short-term risk stratification. Two-hundred-and-eighty-six consecutive patients with chest pain and suspected acute myocardial infarction (AMI) were enrolled in two CCU departments. Serial blood specimens were taken at admission and at 3, 6, 12, 24, 48, 72 and 96 h after admission. According to the biochemical criterion CK-MB mass, the patients were classified as having AMI in 154 patients (54%), unstable angina (UAP) in 72 patients (27%) and no evidence for acute cardiac ischemia in 55 patients (19%). Analytical method comparison of Trop T with cTnT ELISA (cutoff 0.1 microg/L) showed a good agreement, Trop T yielded only 4% false-negative and 3% false-positive results. The diagnostic performance of Trop T for the detection of AMI was only slightly inferior compared to cTnT ELISA. Beyond 12 h after admission, Trop T and cTnT ELISA maintained a sensitivity close to 100%, whereas the sensitivity of the other cardiac markers decreased sharply. The diagnostic sensitivity of Trop T for the detection of minor myocardial damage in UAP patients was the same as for cTnT ELISA. Death within 30 days' follow-up occurred only in AMI patients with a positive Trop T test result within the first 6 h after admission. The admission Trop T and cTnT ELISA were the only significant biochemical predictors of major cardiac events. In conclusion, these data show that Trop T has similar diagnostic sensitivity as cTnT ELISA and is a useful tool to confirm acute or subacute myocardial infarction. Trop T is an excellent marker in detecting minor myocardial damage in UAP patients and is suitable for short-term risk stratification.     

Ability of myoglobin to predict mortality in patients admitted for exclusion of myocardial infarction

Background

Myoglobin can be used as an early marker to diagnose myocardial infarction (MI); and although nonspecific for myocardial necrosis, it seems to be a strong mortality predictor. Because myoglobin elevations are often present in patients with renal insufficiency, it is possible that the predictive value of myoglobin is secondary to identifying patients with renal insufficiency.

Methods

Consecutive patients admitted for MI exclusion without ST elevation on the initial electrocardiogram underwent serial assessment of cardiac markers (creatine kinase [CK], CK–myocardial band [MB], and troponin I [TnI]). Myoglobin was assessed at the time of admission and/or 3 hours later. Renal insufficiency was defined as a creatinine clearance <60 mL/min. Multivariate analysis was performed to identify predictors of 30-day and 1-year all-cause mortality.

Results

A total of 3461 patients were included in the analysis. Overall 30-day and 1-year mortality was 2.4% and 9.7%. Myoglobin was elevated in 675 (20%), CK-MB in 421 (12%), and TnI in 517 (15%). Among the 993 patients with renal insufficiency, myoglobin was elevated in 43%, CK-MB in 17%, and TnI in 21%. Independent predictors of 30-day and 1-year mortality were similar and included age ≥65 years, prior MI, and an ischemic electrocardiogram, whereas myoglobin was the strongest multivariate predictor (odds ratio [OR] 2.8, 95% confidence interval [CI] 2.1-3.7), including those with renal insufficiency (OR 2.3, 95% CI 1.6-3.4). Troponin I had borderline predictive value (P = .08, OR 1.4, 95% CI 0.96-2.0), whereas CK-MB was not predictive in either group.

Conclusions

Despite the absence of cardiac specificity, an elevated myoglobin strongly predicts mortality, even in patients with renal insufficiency.     

The sensitivity of cardiac markers: an evidence-based approach.

The aim of this study was to determine whether, using an evidence-based approach, the results of the papers found in the literature are valid and sufficiently scientifically rigorous to be used to definitely address the problem of cardiac marker sensitivity in detection of acute myocardial infarction. In particular, the diagnostic sensitivities of myoglobin, creatine kinase (CK)-MB isoenzyme, determined as mass concentration, CK-MB isoforms, and of the two cardiac troponins, troponin I and troponin T, were reviewed using a priori formulated inclusion/exclusion criteria for judging the eligibility of studies to be included in the analysis. A clear final message derived from this systematic analysis is the unacceptably poor diagnostic sensitivity of all evaluated markers at patient admission, with substantial failure rate to rule out myocardial infarction at this time. Myoglobin is at present the most sensitive of the markers studied for excluding early AMI with an optimum timing of sampling at patient presentation and approximately 4 h later. However, this marker cannot be used by itself as a proportion of patients admitted to the hospital with a late infarction could be missed. The early rate of rise of CK-MB mass and troponin T is similar. Maximum sensitivity of these two parameters is achieved by the analysis of a second sample 6 to 12 h after admission. Additional larger studies are needed to address the question which troponin shows earlier release after myocardial damage, and to clarify the role of CK-MB isoforms as a possible early marker of myocardial infarction.     

The antibody configurations of cardiac troponin I assays may determine their clinical performance

BACKGROUND: Previous studies have shown superior clinical performance of the cardiac troponin I (cTnI) assay from Beckman-Coulter Diagnostics. This assay had a unique combination of monoclonal antibodies with 2 monoclonal antibodies directed against epitopes near the NH(2) terminus of the heart-specific region of troponin I. The approach has been adopted by the new cTnI assay from Abbott Diagnostics. The aim of our study was to investigate whether this approach affects the clinical performance of cTnI assays. METHODS: Cardiac troponin concentrations were measured in a random sample of patients with unstable coronary artery disease included in the GUSTO IV trial (n = 696) by the AccuTnI (Beckman-Coulter Diagnostics), Architect cTnI (Abbott Diagnostics), Immulite 2500 cTnI (Diagnostics Products Corporation), and Elecsys 2010 cTnT (Roche Diagnostics) assays and related to the 1-year mortality. The primary cutoff concentrations were based on the 99th percentile upper reference limits and an imprecision (CV) < or =10%. RESULTS: The sensitivities of the AccuTnI and Architect cTnI assays in identifying patients who died within 1 year were equal and were significantly higher (P <0.05) than those of the Immulite 2500 cTnI and the Elecsys cTnT assays. The concordance between the AccuTnI and Architect cTnI assays was 97%, but concordances between the Architect cTnI and the Elecsys cTnT assays were 89%-92% with more at-risk patients (P <0.01 to P <0.001) identified by the Architect cTnI assay. CONCLUSIONS: The Architect cTnI assay has clinical performance similar to that of the AccuTnI, probably as a result of the inclusion of a monoclonal antibody against troponin I epitope 41-49 in the assay.     

Evaluation of point-of-care test systems using the new definition of myocardial infarction

OBJECTIVES: To examine the proportion of patients admitted to CCU because of chest pain with a negative quantitative troponin t-test (Cardiac reader; Roche), who despite the negative test, would fulfil the new myocardial infarction criteria. A second aim was to evaluate the clinical utility of troponin I. DESIGN AND METHODS: Troponin T (Cardiac reader; Roche) was measured 12 h after the last chest pain episode. If Troponin T was negative the subjects were included in the study. All included subjects were also examined with troponin I (Stratus CS; Dade Behring) and troponin T at the central laboratory (Elecsys 2010) at the same time. 187 patients were included. CKMB was also measured 6 h after the last chest pain (Stratus CS; Dade Behring). RESULTS: Fifteen patients (8.0%) fulfilled the criteria of myocardial infarction, despite a negative Troponin T (Cardiac reader; Roche). CKMB measures did not add useful diagnostic information. The sensitivity and specificity were 100% and 95.3%, respectively for troponin I, when 0.2 microg/L was used as cut off level for myocardial infarction. CONCLUSION: In this low risk group, eight percent of the patients with a negative Troponin T (Cardiac reader; Roche) fulfilled the new criteria of myocardial infarction. Troponin I (Stratus CS; Dade Behring) appeared to be a reliable method in this group.     

急性心肌梗死早期患者3种血清测定及意义

目的探讨血清肌酸激酶同工酶-MB(CK-MB)、肌红蛋白(Myo)和人心肌肌钙蛋白I(CTnI)检测在急性心肌梗死(AMI)早期诊断中的意义。方法以40例健康体检者作对照,检测85例高度疑为AMI的患者在发病6 h内检测3个血清指标水平。比较其对AMI诊断的性能,以进行优化组合检测。结果 AMI患者在发病6 h内,CK-MB、Myo和CTnI的敏感性分别为82.35%、100.00%和92.64%;特异性分别为94.74%、89.47%和100.00%;单项比较:敏感度和阴性预期值以Myo最高,特异度、阳性预期值和可靠性则以CTnI最佳;并联组合比较:敏感度、特异度、阳性预期值和阴性预期值均以CTnI与Myo最理想;可靠性则以CTnI与CK-MB联合最好;串联组合比较:5项指标均以CTnI与Myo串联检测为最佳。结论血清CTnI在AMI早期诊断中具有良好的灵敏度、特异性和可靠性。CTnI和Myo联合检测可提高对AMI早期诊断的性能。     

Laboratory diagnosis of patients with acute chest pain.

The enzyme activities of creatine kinase (CK), its isoenzyme MB (CK-MB) and of lactate dehydrogenase isoenzyme 1 (LD-1) have been used for years in diagnosing patients with chest pain in order to differentiate patients with acute myocardial infarction (AMI) from non-AMI patients. These methods are easy to perform as automated analyses, but they are not specific for cardiac muscle damage. During the early 90's the situation changed. First creatine kinase MB mass (CK-MB mass) replaced the measurement of CK-MB activity. Subsequently cardiac-specific proteins troponin T (cTnT) and troponin I (cTnI) appeared on the scene, displacing LD-1 analysis. However, troponin concentrations in blood increase only from four to six hours after onset of chest pain. Therefore a rapid marker such as myoglobin, fatty acid binding protein or glycogen phosphorylase BB could be used in early diagnosis of AMI. On the other hand, CK-MB isoforms alone may also be useful in rapid diagnosis of cardiac muscle damage. Myoglobin, CK-MB mass, cTnT and cTnI are nowadays widely used in diagnosing patients with acute chest pain. Myoglobin is not cardiac-specific and therefore requires supplementation with some other analyses such as troponins to support the myoglobin value. Troponins are very highly cardiac-specific. Only the sera of some patients with severe renal failure, which requires hemodialysis, have elevated cTnT and/or cTnI without there being any evidence of cardiac damage. On the other hand, the latest studies have shown that elevated troponin levels in sera of hemodialysis patients point to an increased risk of future cardiac events in a similar manner to the elevated troponin values in sera of patients with unstable angina pectoris. In addition, the bedside tests for cTnT and cTnI alone or together with myoglobin and CK-MB mass can be used instead of quantitative analyses in the diagnosis of patients with chest pain. These rapid tests are easy to perform and they do not require expensive instrumentation. For routine clinical laboratory practice we suggest that in diagnosis of patients with chest pain, myoglobin and CK-MB mass measurements should be performed whenever they are requested (24 h/day) and cTnT or cTnI on admission to the hospital and then 4-6 and 12 hours later.     

Utility of Troponin I in Patients with Cocaine-associated Chest Pain

Baseline electrocardiogram abnormalities and market elevations not associated with myocardial necrosis make accurate diagnosis of myocardial infarction (MI) difficult in patients with cocaine-associated chest pain. Troponin sampling may offer greater diagnostic utility in these patients. OBJECTIVE: To assess outcomes based on troponin positivity in patients with cocaine chest pain admitted for exclusion of MI. METHODS: Outcomes were examined in patients admitted for possible MI after cocaine use. All patients underwent a rapid rule-in protocol that included serial sampling of creatine kinase (CK), CK-MB, and cardiac troponin I (cTnI) over eight hours. Outcomes included CK-MB MI (CK-MB >or= 8 ng/mL with a relative index [(CK-MB x 100)/total CK] >or= 4, cardiac death, and significant coronary disease (>or=50%). RESULTS: Of the 246 admitted patients, 34 (14%) met CK-MB criteria for MI and 38 (16%) had cTnI elevations. Angiography was performed in 29 of 38 patients who were cTnI-positive, with significant disease present in 25 (86%). Three of the four patients without significant disease who had cTnI elevations met CK-MB criteria for MI, and the other had a peak CK-MB level of 13 ng/mL. Sensitivities, specificities, and positive and negative likelihood ratios for predicting cardiac death or significant disease were high for both CK-MB MI and cTnI and were not significantly different. CONCLUSIONS: Most patients with cTnI elevations meet CK-MB criteria for MI, as well as have a high incidence of underlying significant disease. Troponin appears to have an equivalent diagnostic accuracy compared with CK-MB for diagnosing necrosis in patients with cocaine-associated chest pain and suspected MI.     

Cardiac troponin T in diagnosis of acute myocardial infarction

Troponin T is a structurally bound protein found in striated muscle cells. We tested concentrations of its cardiac-specific isotype in peripheral venous blood samples serially drawn from 72 patients with confirmed myocardial infarction. Fifty-nine patients received thrombolytic treatment with intravenous streptokinase, urokinase, or recombinant tissue-type plasminogen activator; because of contraindications, the remaining 13 patients did not. Concentrations of troponin T in plasma, measured by an enzyme-linked immunosorbent assay, started increasing within a few hours after the onset of symptoms (median, 4 h; range, 1-10 h). The sensitivity of troponin T for detecting myocardial infarction was 100% from 10 to 120 h after the onset of symptoms; sensitivity on the seventh day after admission was 84%. Concentrations were increased for up to three weeks in some patients with late or high peak values. Successful reperfusion in Q-wave infarction obviously influences the release of troponin T into plasma, with all such cases showing peak values less than or equal to 26 h (median, 14 h) after the onset of symptoms. Troponin T concentrations in these patients returned to within the reference interval more rapidly than in nonreperfused subjects. In the 13 patients without fibrinolytic therapy, troponin T tended to peak approximately 48 h (median) after the onset of chest pain. Troponin T concentrations in patients for whom thrombolysis was unsuccessful resembled those in patients without fibrinolytic therapy. The specificity of the assay was 96% as tested in samples of 96 emergency-room patients. The reference interval (less than 0.5 micrograms/L) was established from samples of 100 healthy blood donors. Troponin T measurements are a specific and sensitive method for the early and late diagnosis of acute myocardial infarction and could, therefore, provide a new criterion in laboratory diagnosis of its occurrence.     

心肌标志物检测在早期诊断急性心肌梗死中的价值

目的探讨胶体金免疫层析法检测血清肌钙蛋白Ⅰ、肌酸激酶同工酶（CK-MB）、肌红蛋白在急性心肌梗死（AMI）患者早期不同时间段的诊断价值。方法收集该院2011年1月至2012年12月收治的89例AMI病例,根据发病时间分为两组,2～〈6h组42例,6～12h组为47例,非心肌梗死对照组70例。采用血清肌钙蛋白Ⅰ、CK-MB、肌红蛋白三合一诊断试剂对选取的病例进行测定。结果AMI患者肌钙蛋白Ⅰ、CK-MB、肌红蛋白的阳性率均高于对照组（P〈0．05）,在2～〈6h时间段内三者的敏感度分别为35．7％、64．3％、52．4％,均低于6～12h时间段的48．9％、85．1％、76．6％,结果差异有统计学意义（P〈0．05）。CK-MB用于诊断的敏感度在两个时间段内分别为：64．3％、85．1％,较肌钙蛋白I（35．7％、48．9％）、肌红蛋白（52．4％、76．6％）高,差异有统计学意义（P〈0．05）,而肌红蛋白敏感度较肌钙蛋白Ⅰ高（P〈0．05）。将三者联合测定时,阳性率高于单独测定时的阳性率,2～6h组阳性率为69．0％,6～12h组阳性率为89．4％。结论在AMI早期,肌钙蛋白Ⅰ、CK-MB、肌红蛋白单独测定阳性率较低,不能满足临床需要,而采用胶体金法心肌三合一诊断试剂盒,对肌钙蛋白Ⅰ、CKMB、肌红蛋白进行联合测定能提高AM1的早期诊断阳性率,以便为临床提供可靠的实验信息,及时采取有效的治疗措施,从而降低患者的病死率。     

Role of cardiac troponin I in the evaluation of myocardial injury

Cardiac troponin I (cTnI) is highly specific for cardiac muscle. In this study, we compared the utility of CK and CK-MB index versus cTnI in the assessment of myocardial infarction in 155 patients being evaluated for myocardial damage. As a cardiac marker for MI, Troponin I seems to be superior to CK-MB. In the subset of patients with renal disease, cTnI has definite advantages over CK-MB. In addition, the use of cTnI has the potential to replace the measurement of lactate dehydrogenase isoenzymes. J. Clin. Lab. Anal. 12:276–279, 1998. © 1998 Wiley-Liss, Inc.     

心型脂肪酸结合蛋白在急性心肌梗死早期诊断中的价值

目的探讨血清心型脂肪酸结合蛋白(H-FABP)在急性心肌梗死(AMI)早期诊断中的临床应用价值。方法随机选择110例临床疑似AMI胸痛患者,采用时间分辨免疫荧光测定法(TRIFA)检测患者入院即刻血清中H-FABP含量,并与心肌肌钙蛋白I(cTnI)、肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)、超敏C反应蛋白(hsCRP)和肌红蛋白(MYO)进行比较;对11例患者入院即刻和入院6 h后进行动态分析;以60例体检健康者作对照,绘制各心肌损伤标志物受试者工作特征(ROC)曲线并进行曲线下面积(AUC)比较,分析6种心肌损伤标志物诊断早期AMI的敏感度和特异度。结果 AMI患者入院即刻各心肌损伤标志物的AUC由大到小依次为H-FABP、hsCRP、cTnI、CK-MB、CK和MYO,最佳临界值诊断灵敏度分别为85.0%、78.7%、81.3%、73.8%、72.5%和61.3%,特异度分别为93.3%、95.0%、93.3%、100.0%、100.0%、98.3%。H-FABP的AUC与hsCRP、cTnI比较差异无统计学意义(P>0.05),与CK-MB、CK、MYO比较差异有统计学意义(P<0.05)。H-FABP诊断早期AMI的阳性率达85.0%。结论 H-FABP对于AMI早期诊断具有相对较早的检测窗口期和相对较好的特异度,在时效性、灵敏度和特异度等方面具有综合优势,可作为AMI早期诊断或排除诊断的血清标志物。多项心肌损伤指标联合检测可提高AMI实验室诊断的灵敏度、特异度及准确性。