Serum CK-MB isoenzyme after aortic and mitral valve replacements

A release of the MB fraction of creatine kinase (CK) enzyme into the serum due to myocardial manipulation and trauma occurs in patients undergoing cardiac surgery. Thus, the appearance of CK-MB activity as such is not sufficient to indicate of perioperative myocardial infarction. The mean (+/- SD) serum CK-MB isoenzyme level was 95 +/- 103 U/l 18 hours after aortic or mitral valve replacement in 76 patients. Thirteen patients undergoing closure of an atrial septal defect served as controls. They had a significantly lower (p less than 0.01) isoenzyme level postoperatively: 45 +/- 39 U/l. Two patients had the ECG changes of definite myocardial infarction after valve replacement and they also showed high CK-MB values, while the other patients with high enzyme level had no ECG signs suggesting acute infarction. CK-MB values correlated with the aortic cross-clamping time (r = 0.39, p less than 0.001) and weakly with the precordial ECG voltage of SV1 + RV5 (r = 0.25, p less than 0.01). While these findings may reflect the sensitivity of a thick myocardial wall to ischaemia during surgery, the postoperative recovery was not related to the serum CK-MB level.     

心肌坏死标志物联合检测在急性心肌梗死早期诊断及鉴别中的意义

目的探讨心肌坏死标志物联合检测在急性心肌梗死早期诊断及鉴别中的意义。方法选取20lO年12月至2013年5月我院收治的90例患者,其中45例被确诊为急性心肌梗死,设为观察组,其余45例疑似急性心肌梗死的患者经过心电图、彩色多普勒超声心动图检查未见异常,最终确定为非急性心肌梗死患者,设为对照组。对两组患者进行酶活性、心肌蛋白及同工酶电泳检查。采用免疫抑制法测定肌酸激酶（CK）、肌酸激酶同工酶（CK—MB）,采用电化学发光法检测肌钙蛋白l（cTnI）和肌红蛋白（MYO）,记录CK、CK—MB、cTnI和MYO等含量,比较观察组患者心肌标志物不同时间的变化并进行统计学分析。结果与对照组比较,观察组患者血清CK、CK—MB、cTnI及MYO含量升高明显,其中CK、MYO含量升高最为显著（P〈0．05）。CK、CK—MB在发病3-6h后快速升高,均于24h左右达高峰,经治疗3-5天后恢复;cTnI前24h与CK—MB同步,但在血中维持时间较长;MYO在发病后12h发生异常,12h内达到峰值（P〈0．05）。结论心肌坏死标志物联合检测可以提高急性心肌梗死检出率,有助于急性心肌梗死早发现、早诊断和早治疗。     

Influence of autoantibodies to creatine kinase-BB on assays for MB isoenzyme

We describe the influence of autoantibodies that bind creatine kinase BB (CK-BB) on the methods for MB isoenzyme. If these autoantibodies are present in patients' sera, they cause the formation of macro CK type 1 (immunoglobulin-linked CK-BB). In some of these cases they can bind not only endogenous CK-BB but also CK-MB without significantly affecting enzyme activity. Although these antibodies show distinctly less affinity for CK-MB than for CK-BB, they nevertheless bind CK-MB in these particular sera, because their concentration exceeds that of CK-BB isoenzyme. If a person with such autoantibodies has an acute myocardial infarction, the immunoinhibition method for CK-MB, which does not discriminate between CK-MB and CK-BB, will recognize the increase and peak of CK-MB with time, although persistent macro CK activity will be superimposed on the typical isoenzyme pattern. However, isoenzyme electrophoresis and recently introduced immunoenzymometric assays for CK-MB in these cases may be less sensitive for detecting myocardial infarctions, because the typical increase in CK-MB activity may be identified later in the progression of symptoms, or even be missed.     

川崎病患儿血清心肌肌钙蛋白Ⅰ变化及临床意义

目的 :探讨心肌肌钙蛋白Ⅰ (cTnI)在川崎病急性期心肌损伤的诊断价值。方法 :检测川崎病 (KD)组 (n =5 6 )及对照组(n =2 0 )患儿血清cTnI、肌酸激酶 (CK)、肌酸激酶同功酶 (CK -MB)、乳酸脱氢酶 (LDH)浓度。结果 :KD组与对照组血清CK、LDH浓度无显著差别 (P >0 .0 5 ) ,而血清cTnI、CK -MB浓度明显高于对照组水平 (P <0 .0 0 1)。在诊断KD患儿急性期心肌损伤上cTnI优于CK -MB(P <0 .0 5 )。结论 :cTnI与CK -MB对KD患儿急性期心肌损伤有诊断价值 ;与CK -MB比较 ,cTnI具有高度特异性、灵敏度 ,指导早期IVIG治疗 ,从而减少KD患儿心血管并发症的发生。     

Increased activity of creatine kinase isoenzyme MB in a theophylline-intoxicated patient

A 78-year-old woman had increased activities of creatine kinase (CK; EC 2.7.3.2) and CK-MB isoenzyme in her serum, associated with severe theophylline intoxication. The time course for CK-MB activity was similar to that from an acute myocardial infarction. Clinical findings, however, including electrocardiograms, did not support the diagnosis of myocardial infarction. We suggest caution in interpreting CK-MB results in severe theophylline intoxication.     

Using troponin T to diagnose acute coronary syndromes

Elevated troponin T is a useful marker for acute myocardial infarction: it is more specific than is elevated creatine kinase MB isoenzyme, and it remains elevated for many days after creatine kinase levels have returned to normal, providing a useful indicator for late presentations. Nevertheless, creatine kinase MB still has many important roles, including providing estimates of infarct size and diagnosing acute myocardial infarction in patients with renal failure. Often, measuring both markers provides additional information. This article provides a diagnostic algorithm for using both markers.     

Comparison of enzyme immunoassay and immunoprecipitation for creatine kinase MB in diagnosis of acute myocardial infarction

We compared the clinical performance of measuring creatine kinase (EC 2.7.3.2) isoenzyme MB by use of an enzyme immunoassay (Enzygnost CK-MB, Behring Diagnostics) with an immunoprecipitation method (Isomune-CK, Roche Diagnostics) for the diagnosis of acute myocardial infarction. Sera from 80 patients admitted to the coronary care unit because of chest pain were examined: 40 who had this diagnosis of myocardial infarction, and 40 in whom it was ruled out. In addition, sera from 40 apparently healthy individuals were examined. The clinical sensitivity and specificity of these methods were evaluated by use of receiver operating characteristic curves. We conclude that for clinical efficiency, this enzyme immunoassay is slightly superior to the immunoprecipitation assay we used, because of its greater analytical sensitivity and precision for measuring the mass of the isoenzyme.     

Unexplained increase in serum creatine kinase isoenzyme MB activity in a lung cancer patient

In this case of mixed small cell--large cell cancer of the lung in an elderly woman, creatine kinase (EC 2.7.3.2) isoenzymes were assayed serially because of chest pain. The proportions of serum CK-BB and CK-MB isoenzyme activities were persistently above normal (CK-MB 10-18%, normal less than 5%). Electrocardiograms revealed no signs of ischemia or infarction. At autopsy no gross or microscopic infarction or inflammation of the heart was seen. There was also no infarction of smooth or skeletal muscle. The tumor was the probable source of most of the circulating CK-MB isoenzyme. Future cases may pose a similar diagnostic dilemma: differentiating creatine kinase that is present as a result of myocardial infarction from tumor-related CK-MB. Whether or not CK-MB assay could be useful in detecting tumors remains to be investigated.     

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.     

Apparent elevation of serum CK-MB not due to acute myocardial infarction.

An increased serum level of the MB isoenzyme of creatine kinase (CK-MB) is a useful marker for acute myocardial infarction. Although described extensively in clinical chemistry literature, there is little information in standard medical references about false positives for this test. We report two cases where high levels of measured CK-MB activity were in fact due to another form of CK, associated with internal malignancy.     

Diagnostic efficacy of a new enzyme immunoassay for creatine kinase MB isoenzyme

A new commercial enzyme immunoassay kit for quantification of creatine kinase-MB (CK-MB) isoenzyme was compared with its electrophoretic determination with respect to efficacy in diagnosis of acute myocardial infarction. Enzygnost CK-MB (Behring Diagnostics) is a solid-phase "sandwich"-type enzyme immunoassay with antibodies to the B-subunit coated on plastic tubes and peroxidase-conjugated antibodies to the M-subunit added after incubation with sample. This kit is designed to measure only CK-MB and not CK-MM, CK-BB, adenylate kinase, or atypical CK molecules. The linear-regression equation comparing the two methods was: Enzygnost = 0.98 . electrophoresis - 0.72, with a correlation coefficient of r = 0.967 (n = 143). For 51 patients admitted for diagnosis of possible acute myocardial infarction, the Enzygnost kit achieved 100% sensitivity, specificity, and efficiency in predicting the correct diagnosis. Corresponding values for the electrophoretic assay were: 95.5% sensitivity, 93.1% specificity, and 94.1% efficiency. We conclude that this kit method provides an excellent alternative to electrophoresis.     

Increased activities of creatine kinase and lactate dehydrogenase isoenzymes in a patient with metastatic ovarian tumor

A 50-year-old woman with metastatic rhabdomyosarcoma of the ovary had increased activities of creatine kinase (CK; EC 2.7.3.2), CK-MB isoenzyme, lactate dehydrogenase (LD; EC 1.1.1.27), and LD-2 isoenzyme in her serum. The isoenzyme activities did not show a pattern of increasing, then decreasing. Clinical findings, including electrocardiograms, did not support the diagnosis of myocardial infarction. We suggest that high activities of CK-MB and LD-2 in serum may serve as a marker of rhabdomyosarcoma.     

IgA-CK-BB complex with CK-MB electrophoretic mobility can lead to erroneous diagnosis of acute myocardial infarction

This patient, on admission, presented with a tentative diagnosis of myocardial infarction: the electrocardiogram showed a nonspecific ST-segment and T-wave abnormalities, and total creatine kinase (CK; EC 2.7.3.2) activity was slightly increased (238 U/L). However, a high electrophoretic value for CK-MB (50% of total CK activity) and the electrophoretic pattern of lactate dehydrogenase (EC 1.1.1.27) isoenzymes ruled out myocardial infarction. The isoenzyme migrating as CK-MB was found later to contain no immunologically normal CK-M subunits, and it was bound to IgA. A mixture of the patient's serum and a human serum control containing all CK isoenzymes showed altered electrophoretic mobility only for CK-BB, indicating that the patient's serum contained antibodies to the B unit of CK. Elution from a Sephadex G-200 column showed that the peak at which most of the anodic CK was eluted corresponded to a molecular mass of approximately 200 kDa. Evidently this atypical isoenzyme was an IgA-CK-BB complex. Because this macro CK type 1 can mimic CK-MB, it may therefore be a source of confusion.     

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Cardiac enzyme levels are more sensitive and specific in confirming or excluding the diagnosis of acute myocardial infarction than are historical or electrocardiographic criteria. Several enzymes are elevated after infarction, but total creatine kinase, the MB isoenzyme of creatine kinase, and lactate dehydrogenase are the most useful. Dr Ruzich explains how serial determinations and attention to appearance, peak, and disappearance times of these enzymes help identify elevation that is unrelated to infarction.     

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。     

手足口病患儿心肌酶谱检测分析

目的探讨小儿手足口病(HFMD)患儿心肌酶谱的改变及其临床意义。方法对佛山市第二人民医院187例HFMD患儿于诊断次日和病程结束后,进行天门冬氨酸氨基转移酶(AST)、乳酸脱氢酶(LDH)、肌酸激酶(CK)和肌酸激酶同工酶(CK-MB)检测,并分析其临床意义。结果 HFMD患儿与健康儿童比较心肌酶谱明显升高(P<0.01),且心肌酶谱异常治疗前亦明显高于治疗后(P<0.01),但均无心肌炎表现。结论提示HFMD病程中心肌较易受到侵犯,经治疗后预后较好。     

Increased creatine kinase MB in the absence of acute myocardial infarction

Although measurement of CK-MB is a very sensitive, specific, and cost-effective test for use in diagnosis or exclusion of acute myocardial infarction, it should not be used as the sole diagnostic indicator, and all positive values must be critically analyzed to exclude other causes of increased values in serum. This is particularly important when the population being tested consists of patients with multiple medical problems, with low to medium probability of myocardial infarction, and without clinical or other biochemical (i.e., LDH 1) evidence of acute myocardial infarction. When the temporal pattern and absolute CK-MB values are considered together with the patient's clinical status, the diagnostic specificity is dramatically increased. In addition, one must be familiar with the limitations of individual assay systems in order to exclude method-related artifactual values.     

AMI患者早期CK同工酶亚型的高压电泳图谱分析

目的探讨CK同工酶亚型在AMI胸痛发作后24h内的变化规律,为AMI患者的早期诊断提供依据。方法采用REP全自动高压电泳仪检测AMI胸痛发作后不同时间以及对照组的CK-MM1、CK-MM2、CK-MM3、CK-MB1、CK-MB2等指标并进行荧光扫描,同时在Olympus2700全自动生化分析仪上测定CK、CK-MB的总活性,对所得数据进行恰当的统计分析。结果在AMI患者胸痛发作24h内,CK同工酶亚型有一特殊的变化规律:4~6h内,CK-MB2、CK-MM3开始升高,8~12h达高峰,92%的病人CK-MB2/CK-MB1>1.5,同时91%的病人CK-MM3/CK-MM1>0.5。结论CK同工酶亚型CK-MM3/CK-MM1、CK-MB2/CK-MB1的检测可作为AMI早期诊断的指标。     

Lactate dehydrogenase isoenzyme 1: Its usefulness as a screening test in diagnosis of myocardial infarction

Immunological assay of LD-1 activity provides a quantitative measurement of the type of lactate dehydrogenase (LD, EC 1.1.1.27) activity characteristic of myocardial origin. Using this test, a laboratory diagnosis of myocardial infarction can be either ruled out or confirmed in approximately 75% of patients in whom this diagnosis is suspected, without electrophoretic separation of creatine kinase (CK, EC 2.7.3.2.) and LD isoenzymes. Normal total CK and LD activities cannot be used to rule out myocardial infarction since CK-MB and LD-1 may have increased although total activities remain within their reference ranges. LD-1 activity increases as quickly as CK-MB following the onset of pain in the majority of patients but it remains elevated longer giving a greater period of time during which the diagnosis of myocardial infarction can be confirmed.     

心肌酶谱及其比值与肌钙蛋白定量测定对儿童病毒性心肌炎的诊断价值

目的初步了解重庆市主城区儿童心肌酶的正常范围,探讨其比值及肌钙蛋白Ⅰ(cTnI)测定对儿童病毒性心肌炎的诊断价值。方法采用OLYMPUS 400全自动生化分析仪测定肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)、乳酸脱氢酶(LDH)、α-羟丁酸(αHBDH)并计算出CK-MB/CK、αHBDH/LDH比值;CK采用酶耦联测定法,αHBDH、LDH采用连续监测法,CK-MB采用免疫抑制法,cTnI采用胶乳增强免疫比浊法测定。结果 200名健康儿童心肌酶水平均高于健康成人(P<0.01),但不同组别CK-MB/CK<0.03者占80%以上,αHBDH/LDH在0.7～0.9之间占85%以上。80名健康儿童运动后的心肌酶普遍高出儿童正常范围,但其比值并未升高。已确诊的132例儿童病毒性心肌炎患者中心肌酶异常者107例(占80%),CK-MB/CK>0.07者80例,αHBDH/LDH>0.9者78例,cTnI结果阳性90例。其比值和cTnI结果经配对检验存在一致性关联。结论不能用成人的标准来判断儿童心肌酶异常,儿童心肌酶单项升高不能作为病毒性心肌炎的诊断依据;CK-MB/CK>0.07、αHBDH/LDH>0.9以及cTnI结果阳性对诊断病毒性心肌炎有极大的临床价值。