心肌肌钙蛋白Ⅰ免疫层析试纸条的研制

目的制备人心肌肌钙蛋白Ⅰ免疫层析试纸条,建立一种快速检测人心肌肌钙蛋白I的检测方法。方法采用柠檬酸三钠还原法制备胶体金,标记肌钙蛋白I单克隆抗体,喷于玻璃纤维纸上制成胶体金结合物垫。将另一株肌钙蛋白I单克隆抗体和抗鼠二抗分别喷于试纸条的检测线和质控线处,组装成试纸条并进行灵敏度、特异性及临床样品测定。结果该试纸条检测灵敏度为1μg/L,15min内可判断结果;与C-反应蛋白、人心肌脂肪酸结合蛋白、肌酸激酶、人心肌肌红蛋白无交叉反应;测定健康人血清样本40例,结果均为阴性;测定14例心肌梗死患者血清,结果均为阳性,且T线显色程度与发光法测定值呈正相关。结论该试纸条灵敏度高、特异性强、操作简便,结果判断直观,可用于急性心肌梗死的早期筛查。     

Evaluation of the chemiluminescence immunoassays for the measurement of troponin I, myoglobin and CK-MB using the IMMULITE system in comparison to other measuring systems

We evaluated the chemiluminescence immunoassays for the detection of the cardiac markers troponin I, myoglobin and CK-MB on the IMMULITE System (Diagnostic Products Corporation) in comparison to the same analytes of other companies. The IMMULITE assays are two-site solid phase immunometric assays using a murine monoclonal capture antibody on the solid phase and a polyclonal antibody conjugated with alkaline phosphatase (except CK-MB monoclonal, murine) for detection. Precision was investigated using serum pools with a low, a cutoff and a high concentration of the respective analyte. The results were satisfactory with an intra-assay precision coefficient of variation, CV of 1.7% - 3.2% for troponin I, 2.6% - 5.1% for myoglobin, 2.7% - 5.3% for CK-MB and an interassay precision of 5.1% - 6.9% for troponin I, 5.7% - 7.3% for myoglobin and 3.8% - 8.4% for CK-MB. In linearity studies with various dilution steps, a mean value of 105% was found for troponin I, 103% for myoglobin and 117% for CK-MB. The average recovery was 85% for troponin I, 100% for myoglobin and 95% for CK-MB. The clinical validity of the assays in the diagnosis and therapy of myocardial infarction was investigated in 120 patients who were sent to the hospital with suspected myocardial infarction. Four hours after admission all patients with clinically verified myocardial infarction showed troponin I and troponin T values above the cutoff value. A maximum rate of 32% of the patients (IMMULITE Troponin I) with an instable angina pectoris showed troponin values above the cutoff for myocardial infarction (1.0 microg/L), 4 hours after admission. A cutoff-reduction to 0.2 pg/L for troponin I increased the number of patients to 45%. The negative predictive value was constantly 67%. The results obtained by IMMULITE assays were compared to the Elecsys cardiac assays (Roche Diagnostics) and the AxSYM-cardiac assays (Abbott Diagnostics). The highest correlation (r = 0.99) was found for IMMULITE Troponin I (DPC) and Troponin I (Abbott). The Abbott-Troponin I showed the highest diagnostic sensitivity within 4 hours after admission. All compared methods showed a similar diagnostic sensitivity (close to 100%) > 4 hours after admission. For all investigated methods the percentage of discrepant results decreased to a minimum 4 hours after admission.     

Clinical assessment of specific enzyme immunoassay for the human cardiac myosin light chain II (MLC II) with use of monoclonal antibodies

A highly specific enzyme-linked "sandwich" immunoassay was developed for determining cardiac myosin light chain II (MLC II) in serum by using an anticardiac MLC II monoclonal antibody and a solid phase consisting of glass rods coated with another monoclonal antibody. We can detect as little as 0.2 ng of cardiac MLC II per assay. The measurable range of cardiac MLC II concentration in serum is 1 to 30 micrograms/L. The assay demonstrated no cross-reactivity with a skeletal muscle MLC within the measurable range. The mean coefficients of variation were 6.1% within assay and 5.1% between assay. The concentration of cardiac MLC II in sera from healthy subjects ranged from 0 to 4.0 micrograms/L (mean 0.75 micrograms/L and median 0 micrograms/L). The concentrations of cardiac MLC II in serum of patients with skeletal muscle disease due to various causes (n = 15) and patients with effort angina (n = 25), in general, were not significantly elevated above normal. In all patients with myocardial infarction, the concentrations of cardiac MLC II were over 4.0 micrograms/L at 12 h after onset. The mean (+/- 1 SD) peak concentration of cardiac MLC II was 16.2 (+/- 4.4) micrograms/L at 90 h (mean) after onset. On the 5th day, the cardiac MLC II concentrations in all patients with myocardial infarction were significantly elevated above normal; none showed abnormal MB-creatine kinase (CK-MB) activity at this time. Thus, the measurement of cardiac MLC II concentration in serum may be useful to provide a specific and sensitive diagnosis of myocardial necrosis at any time period following myocardial infarction.     

The levels of serum myoglobin in cardiac patients with elevated creatine kinase-MB and suspected acute myocardial infarction

A monoclonal antibody enzyme immunoinhibition assay was used to quantitate serial serum myoglobin (Mb) levels in 121 patients who had ?5% creatine kinase-MB (CK-MB) and suspected acute myocardial infarction (AMI). Serum Mb levels higher than 0.16 μg/ml were considered abnormal. In 94% of these patients who were finally diagnosed with AMI, Mb levels were higher than 0.16 μg/ml, whereas all 30 normal control blood donors had lower Mb levels. Patients with anterior or inferior wall infarcts had higher Mb levels (?0.64 μg/ml) than patients with lateral or subendocardial infarction. Only 68% (82/ 121) of patients evaluated by elevated CK-MB alone had a final diagnosis of AMI. In contrast, 94% (77/83) of patients who in addition showed elevated Mb had AMI. It is suggested that analysis of Mb levels allows a more accurate diagnosis of AMI in patients with elevated CK-MB than does reliance on CK-MB values alone. © 1993 Wiley-Liss, Inc.     

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.     

Etude de la myoglobinemie et de son evolution au cours de l'infarctus du myocardeStudy on myoglobinemia and its development during myocardial infarction

Thirty six patients suffering from myocardial infarction were investigated by assay of their serum myoglobin, total creatine kinase and creatine kinase isoenzyme MB activities. Determination of serum myoglobin presents, with regard to creatine kinase MB, two major advantages: a very early increase after the onset of the pain (about three hours later) and a very quick clearance, allowing the diagnosis of a second episode of necrosis after about one day.     

Systemic short-term fibrinolysis with high-dose streptokinase in acute myocardial infarction: time course of biochemical parameters

The course of plasma catalytic activities of total creatine kinase, creatine kinase isoenzyme MB, total, cytoplasmatic and mitochondrial aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, glutamate dehydrogenase and concentrations of myoglobin, urea, acidic alpha 1-glycoprotein and creatinine were followed in 33 patients suffering from acute myocardial infarction. All patients were randomized in a double-blind, prospective study. One group (18 patients) was infused with streptokinase 1.5 X 10(6) units/90 minutes; the control group received routine continuous i.v. heparin treatment (1000 units/h). Ten hours after completion of the study protocol, treatment of both groups of patients was continued with heparin, 1000 units/h and Aspisol, 1 g/day2). Streptokinase treatment induced earlier wash-out and therefore earlier peak levels of several enzymes: total creatine kinase (11 hours), creatine kinase isoenzyme MB (6 hours), total and cytoplasmatic aspartate aminotransferase (6 hours) and lactate dehydrogenase (9 hours). Total creatine kinase peak catalytic activity and myoglobin peak concentration were higher in the group receiving thrombolytic therapy. A significantly different course of catalytic activity between both treatment groups was found for total creatine kinase and creatine kinase isoenzyme MB, total and cytosolic aspartate aminotransferase, lactate dehydrogenase and alpha-hydroxybutyrate dehydrogenase. The course of mitochondrial aspartate aminotransferase catalytic activity was different only 12 hours after the beginning of treatment. The shift of several catalytic activities to an earlier peak level in plasma may indicate reperfusion of ischaemic myocardium due to thrombolytic therapy.     

Study of a myoglobin test in patients hospitalized for suspected myocardial infarction

An immunoagglutination latex test was studied in comparison with a plasma myoglobin radioimmunoassay in 103 subjects with suspected myocardial infarction. The test provided an early and reliable indication of raised plasma myoglobin (greater than 85 micrograms/l), a biochemical marker for the early phase (12 h) of myocardial infarction. The diagnostic values (sensitivity and specificity) studied over a 36 h period were the same as those for the plasma myoglobin assay. The sensitivity was similar to that of creatine kinase activity and better than that of the creatine kinase MB/creatine kinase ratio; the lower specificity was due to false-positive results in some subjects with angina. The myoglobin test, which provides rapid results, may be substituted in early diagnosis of myocardial infarction for the plasma myoglobin assay which is unsuitable for emergency analysis.     

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。     

Myoglobin concentration, creatine kinase activity, and creatine kinase B subunit concentrations in serum during thyroid disease

Changes in values for myoglobin, total creatine kinase (EC 2.7.3.2), and creatine kinase B-subunit in the serum of patients with thyroid disease are compared with values for these during the 24-h after myocardial infarction. Concentrations of all three of these muscle-derived proteins were significantly higher than normal in patients with primary hypothyroidism, and declined with treatment. Values for total creatine kinase activity were below-normal in hyperthyroid patients, but increased after treatment. Values for total creatine kinase and, to a lesser extent, myoglobin in hypothyroidism extend into the range of values observed after myocardial infarction. The mechanism of the changes in these analytes in hypothyroidism may be related to increased leakage from skeletal-muscle cells or diminished clearance from the circulation, or both.     

Rapid and sensitive radioimmunoassays for human myoglobin

A radioimmunoassay for quantitation of serum myoglobin in healthy individuals and patients with different diseases is described. Purified myoglobin was labelled by an 125I-labelled ester (N-succinimidyl 3-(-4 hydroxy, 5-[125I]iodophenyl) propionate), a commercially available antiserum was used, and the antigen-antibody complex was precipitated with polyethylene glycol 6000. The rapid assay can be performed within 1 h at 37 degrees C with a detection limit of 45 micrograms/l. Prolonged incubation at 4 degrees C for 18 or 72 h gives a detection limit of 6 and 2 micrograms/l, respectively. The mean coefficient of variation of the routine assay was 11%. In healthy human subjects a significant difference in mean serum myoglobin concentration was found between 43 women (34 +/- 17 micrograms/l) and 51 mean 47 +/- 15 micrograms/l). In twenty patients admitted to hospital with the clinical diagnosis acute myocardial infarction, the serum myoglobin concentration profiles were in close agreement with the final diagnosis. In three patients with myocardial infarction serum samples were taken every 2 h after the acute episode, and serum myoglobin levels were compared with the levels of creatine kinase, lactate dehydrogenase, aspartate aminotransferase and creatine kinase isoenzyme-MB.     

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.     

血清心脏型脂肪酸结合蛋白联合糖原磷酸化酶脑型检测在小儿脓毒症心肌损伤诊断中的临床价值

目的研究小儿脓毒症心肌损伤诊断中血清心脏型脂肪酸结合蛋白(FABP3)联合糖原磷酸化酶脑型(GPBB)检测的应用价值。方法采用回顾性分析方法,研究对象为2019年1月至2020年1月葫芦岛市中心医院收治的87例脓毒症患儿,根据是否出现心肌损伤划分为2组,心肌损伤患儿列入A组,共38例,未出现心肌损伤患儿列入B组,共49例;同时,选取同一时期入院就诊的44例的非脓毒症感染性疾病患儿作为研究对象,列入C组。3组患儿均选取用全自动血气分析仪测定肌红蛋白、肌钙蛋白Ⅰ,并选取酶联免疫吸附实验法测定GPBB、FABP3及肌酸激酶同工酶,比较3组患儿肌红蛋白、肌钙蛋白Ⅰ、GPBB、FABP3及肌酸激酶同工酶水平,并分析心肌损伤指标肌红蛋白、肌钙蛋白Ⅰ、肌酸激酶同工酶与血清FABP3、GPBB相关性。结果A组[(396.85±13.07)ng/mL、(3.08±0.06)ng/mL、(22.78±1.02)ng/mL、(34.45±2.41)ng/mL、(44.08±6.53)U/L]、B组[(68.26±12.45)ng/mL、(0.12±0.04)ng/mL、(9.17±1.08)ng/mL、(13.64±2.52)ng/mL、(20.85±7.01)U/L]患儿肌红蛋白、肌钙蛋白Ⅰ、GPBB、FABP3及肌酸激酶同工酶水平明显高于C组[(17.16±10.09)ng/mL、(0.04±0.03)ng/mL、(2.58±1.02)ng/mL、(4.34±3.02)ng/mL、(9.17±6.73)U/L],差异有统计学意义(P<0.05);A组患儿肌红蛋白、肌钙蛋白Ⅰ、GPBB、FABP3及肌酸激酶同工酶水平明显高于B组,差异有统计学意义(P<0.05)。脓毒症患儿血清FABP3、GPBB与肌红蛋白、肌钙蛋白Ⅰ、肌酸激酶同工酶均呈正相关(r=0.602、0.521;r=0.466、0.494;r=0.528、0.489,P<0.05)。结论小儿脓毒症心肌损伤诊断中血清FABP3联合GPBB检测的应用效果显著,可用于评估脓毒症患儿心肌损伤严重程度。     

Elimination kinetics of myoglobin and creatine kinase in rhabdomyolysis: implications for follow-up

OBJECTIVE: Creatine kinase and myoglobin are markers of muscular damage in rhabdomyolysis. Whereas myoglobin is considered to be the principal compound causing tubular damage, serum creatine kinase level is presently guiding therapeutic interventions in clinical practice to prevent acute renal failure. Because differences in elimination kinetics of these two compounds may influence therapeutic decisions, we studied elimination kinetics of myoglobin and creatine kinase in patients with rhabdomyolysis. DESIGN: Open, noncomparative study. SETTING: Intensive and intermediary care units in a university hospital. PATIENTS: A total of 13 consecutive patients with rhabdomyolysis whose baseline serum creatine kinase exceeded 5000 IU/L. Ten of 13 patients were treated with forced alkaline diuresis, and none were dialyzed. RESULTS: Myoglobin had faster elimination kinetics than creatine kinase (p <.01), and the average times to reach the 50% level of initial values were 12 hrs for myoglobin and 42 hrs for creatine kinase. Elimination of myoglobin was not affected by glomerular filtration rate. Compared with creatinine clearance (mean, 102 mL/min), myoglobin clearance was low (mean, 3 mL/min), both in patients with preserved renal function (n = 11) and in those with acute renal failure (n = 2). CONCLUSION: Serum myoglobin has faster elimination kinetics than creatine kinase in patients treated with forced alkaline diuresis for rhabdomyolysis. Considering the etiologic role of myoglobin, our data suggest that serum myoglobin level, rather than that of creatine kinase, should be used to guide therapy in patients with rhabdomyolysis.     

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。     

Clinical evaluation of the first medical whole blood, point-of-care testing device for detection of myocardial infarction

BACKGROUND: Validation of whole blood, point-of-care testing devices for monitoring cardiac markers to aid clinicians in ruling in and ruling out myocardial infarction (MI) is necessary for both laboratory and clinical acceptance. METHODS: This study evaluated the clinical diagnostic sensitivity and specificity of the First Medical Cardiac Test device operated by nursing and laboratory personnel that simultaneously measures cardiac troponin I (cTnI), creatine kinase (CK) MB, myoglobin, and total CK on the Alpha Dx analyzer in whole blood for detection of MI. Over a 6-month period, 369 patients initially presenting to the emergency department with chest pain were evaluated for MI using modified WHO criteria. Eighty-nine patients (24%) were diagnosed with MI. RESULTS: In whole blood samples collected at admission and at 3- to 6-h intervals over 24 h, ROC curve-determined MI decision limits were as follows: cTnI, 0.4 microgram/L; CKMB, 7.0 microgram/L; myoglobin, 180 microgram/L; total CK, 190 microgram/L. Based on peak concentrations within 24 h after presentation, the following sensitivities (+/- 95% confidence intervals) were found: cTnI, 93% +/- 5.5%; myoglobin, 81% +/- 9.7%; CKMB, 90% +/- 6.3%; total CK, 86% +/- 7.5%. Sensitivities were maximal at >90% for both cTnI and CKMB at >12 h in MI patients, without differences between ST-segment elevation and non-ST-segment elevation MI patients. CONCLUSIONS: The First Medical point-of-care device provides cardiac marker assays that can be used by laboratories and clinicians in a variety of hospital settings for ruling in and ruling out MI.     

The serum selenium concentration of patients with acute myocardial infarction

Serum selenium concentration was determined in 49 patients with acute myocardial infarction within 4 hours after the beginning of the symptoms. The mean serum selenium concentration of the patients was significantly lower than that of healthy controls (55 +/- 15 micrograms/l vs. 78 +/- 11 micrograms/l). Among the 49 patients with acute myocardial infarction 20 (41%) had serum selenium concentration below the 95% percentile of the healthy control group. It is concluded that the low serum selenium concentration was present in these patients before the acute event and was not a consequence of the myocardial infarction. No relationship was found in this study between the serum selenium concentration and the severity of myocardial infarction if the number of coronary vessels occluded is taken as the criterion of severity. Serum selenium concentration was similar in patients with 1 or more coronary vessels occluded. Patients with anterior or posterior myocardial infarction had similar serum selenium concentrations. A positive correlation was observed between serum selenium concentration and total serum creatine kinase (CK) activity and serum myoglobin (MB). The serum selenium concentration correlated negatively with the ratio CK-MB/total CK activity, which can be interpreted as minor injury of mitochondria during infarction in patients with normal serum selenium concentration.     

Use of a dual monoclonal solid phase and a polyclonal detector to create an immunoassay for the detection of human cardiac troponin I

OBJECTIVES: We report the development of a fully automated, random access, chemiluminescent immunoassay, for the detection of human cardiac Troponin I (cTnI) in serum and plasma for use on the ACS:180(R) System. DESIGN AND METHODS: This assay format uses a combination of two monoclonal antibodies covalently coupled to paramagnetic (PMP) particles as a solid phase and an affinity purified polyclonal antibody, specific to the N-terminal domain of cTnI (peptide-3 region) labeled with a chemiluminescent compound as the detector antibody. The assay offers excellent low-end sensitivity and precision. RESULTS: No interferences are observed from by blood components such as HAMA and drugs used in cardiac therapy. Patient samples tested on the ACS:180 cTnI assay showed good correlation with the Stratus cTnI assay (ACS: cTnI = 1. 02*Stratus + 0.05 g/L, r = 0.96, n = 1170). CONCLUSION: Paired with the other ACS:180 cardiac assays, myoglobin and CKMBII, the ACS:180 system now offers an excellent panel of cardiac assay for use in rapid and accurate diagnosis of a myocardial event.     

A new immunoassay for the measurement of myoglobin in serum

Because the concentration of serum myoglobin (Mb) increases within 2 to 4 hours after the first sign of acute myocardial infarction, it has been proposed as an early marker of the condition. Our aim was to evaluate a new assay that provides a rapid, quantitative determination of Mb (Baxter Stratus Myoglobin) based on the radial partition technique. We compared the results obtained by this technique with those from nephelometric and radioimmunoassay methods. A significant agreement was observed, the correlation coefficients (r) being 0.999 and 0.996, respectively. The method evaluated provided good reproducibility with CVs between 3.14% and 4.87%, and its linearity and analytical sensitivity were satisfactory. The clinical evaluation of this assay demonstrates that Mb increases in serum of patients with acute myocardial infarction before total creatine kinase and creatine kinase MB isoenzyme. Mb concentration shows an early peak and earlier return to normal values after the necrosis compared to enzymatic activities. Moreover the assay is rapid and fully automated. The method is therefore considered appropriate for contributing to the early diagnosis of AMI in clinical laboratories. © 1994 Wiley-Liss, Inc.     

Use of creatine kinase MB isoenzyme for diagnosing myocardial infarction when total creatine kinase activity is high

The usefulness of measuring creatine kinase MB isoenzyme for diagnosing myocardial infarction when activities of total creatine kinase are very high is unclear. We conducted a retrospective study in an urban hospital that serves a largely indigent population. We concentrated on 146 patients whose creatine kinase activity was greater than 1000 U/L (upper limit of normal: 165 U/L for women and 225 U/L for men), with MB isoenzyme greater than 10 U/L and less than 5% of total creatine kinase. The positive predictive value of MB isoenzyme (isoimmune method) values greater than 10 U/L was between 11.6% and 56.8% when the value for total creatine kinase exceeded 1000 U/L. Using different values (MB greater than 4% of total creatine kinase) as positive for myocardial infarction would have resulted in far fewer false-positives, but 10 cases of myocardial infarction would have been missed. The most appropriate cutoff value for MB isoenzyme in this population (total creatine kinase greater than 1000 U/L) was found to be greater than 2% of total creatine kinase.