Clinical evaluation of the new creatine kinase MB reagent kit "L-System CK-MB MtO"

The creatine kinase MB (CK-MB) activity assay, which is based on the immunoinhibition method, has long been used in the diagnosis of acute myocardial infarction (AMI) because of its good cost-performance ratio and simplicity. However, the immunoinhibition method can not differentiate between CK-MB and MtCK, and therefore, CK-MB activity determined using this method is higher than the actual value in the sample which MtCK appears; this may lead to the misdiagnosis of AMI. We, therefore, evaluated the analytical and clinical performance of a new CK-MB reagent kit "L-System CK-MB MtO," which can inhibit MtCK. The kit yielded good precision and linearity and no interference from hemolysis, bilirubin or chyle. A good correlation was observed between the values determined using this kit and those determined using the conventional kit for samples of patients with acute coronary syndromes. However, differences were observed in the CK-MB values determined for samples from patients with malignancy. CK isoenzyme analysis indicated that MtCK was present in all these samples. The new method permits the accurate estimation of CK-MB activity in samples of patients with high serum levels of MtCK activity and indicates that the conventional method has a high false-positive rate for CK-MB activity. CK-MB activity in the serum of healthy individuals measured using the new and the conventional kits was 1.9-9.5 U/l and 4.5-15.3 U/l, respectively. The new kit, enables accurate estimation of CK-MB activity and is, therefore, more useful than the conventional kit in the diagnosis of acute coronary syndromes.     

用ROC曲线确定cTnI诊断AMI的临界值

目的：确定肌钙蛋白I（cTnI）定量结果应用于急性心肌梗死（AMI）诊断的临界值,并重新评价其临床意义。方法：用酶联荧光分析法测定本院急诊病人198例,其中符合AMI的诊断标准患者标本96例,健康对照组102例。依据测定结果应用统计软件计算敏感度、特异度、阳性似然比和ROC曲线下的面积并进行分析,对AMI诊断的临界值进行评价。结果：根据统计分析,cTnI用于AMI的最佳诊断临界值为0.12μg/L（敏感度83.33%、特异性94.12%、阳性似然比14.16;ROC曲线下的面积为0.816）。结论：cTnI以0.12μg/L作为诊断AMI的临界值较为合适,可提高其临床诊断的效率。     

Significance of cerebrospinal fluid sIL-2R level as a marker of CNS involvement in acute lymphoblastic leukemia

Soluble IL-2 receptor (sIL-2R), total protein, uric acid, glucose, aspartate aminotransferase (AST) and lactate dehydrogenase (LD) levels were analyzed in 153 (19 cytology(+), 134 cytology(-)) pairs of CSF and serum samples and the data were compared with the results of cytologic examination to find new CSF markers of CNS involvement in 77 patients with acute lymphoblastic leukemia (ALL). The CSF leukocyte count of cytology(+) samples averaged 107.6+/-362.4 cells/microl, and was higher than that of cytology(-) samples (1.0+/-3.4 cells/microl, p=0.001). The CSF sIL2-R level of cytology(+) samples averaged 162.1+/-247.7 U/ml, and was higher than that of cytology(-) samples (11.2+/-44.6 U/ml, p <0.001). The CSF total protein, uric acid, glucose, AST, and LD levels were not significantly different in cytology(+) and cytology(-) samples (p >0.05). ROC curves showed that the discrimination power of CSF sIL2-R for the presence of leukemic blasts was better than that of CSF leukocyte counts. With a cut-off value for CSF sIL2-R at 10 U/ml, the sensitivity was 89.5% and the specificity was 89.6%. With a cut-off value for CSF leukocyte count at 4 cells/microl, the sensitivity and specificity were 47.4% and 63.2%, respectively. In conclusion, CSF sIL2-R level is a valuable marker of CNS involvement in ALL patients; a level of >10 U/ml may serve as an objective indicator of CNS involvement in conjunction with conventional cytology and the CSF leukocyte count.     

快速固相免疫层析法测定心肌肌钙蛋白I及在AMI诊断中的应用

为探讨采用快速固相免疫层析法测定心肌肌钙蛋白Ⅰ(cTnI) 和选择性免疫抑制紫外法测定肌酸激酶同工酶(CK-MB)及在急性心肌梗死(AMI) 诊断中的价值,本文分别对52例AMI患者于胸痛发生后4、8、12、24、48h及第5、7d和26名正常对照者的血清进行了cTnI及CK-MB 的测定.结果表明,AMI组血清cTnI、CK-MB 的测定值均明显高于正常对照组,具有显著性差异(P<0.01 );AMI患者cTnI在4h及第5、7d时的阳性率均明显高于CK-MB,具有显著性差异(P<0.01 ).以上数据表明,cTnI在诊断急性心梗中具有较高的灵敏度及高度特异性,尤其是采用快速固相免疫层析法检测cTnI,可为快速诊断AMI提供依据,具有临床应用价值.     

敏感型心肌钙蛋白T对早期诊断急性心肌梗死的价值

目的探讨敏感型心肌钙蛋白T（hs-cTnT）对早期诊断急性心肌梗死（AMI）的临床应用价值。方法应用发光免疫法分别测定67例AMI患者和58例非AMI患者,同一份血清标本作标准型心肌钙蛋白I（cTnI）和hs-cTnT检测。结果标准型cTnI检测AMI患者的敏感度和特异性分别为68.7%和53.4%,hs-cTnT为74.6%和51.7%。hs-cTnT检测的接受者操作特征（ROC）曲线下面积（AUC）和诊断灵敏度分别为0.659和70.2%,均高于标准型cTnI检测的0.639和59.7%;标准型cTnI检测的最佳cutoff值为0.035μg/L,hs-cTnT检测为0.0125μg/L。结论应用hs-cTnT早期诊断AMI的准确性和灵敏度优于标准型cTnI的检测。     

Usefulness of cardiac troponin I in patients with acute myocardial infarction

Cardiac troponin(cTn) is a sensitive marker for acute myocardial infarction(AMI). However, some cases of renal failure have been reported to show false positive results for cardiac troponin T(cTnT). Recently, it has been reported that heart-type fatty acid-binding protein(H-FABP) is a sensitive marker for AMI in the early phase. We evaluated the usefulness of cardiac troponin I(cTNI) using serum samples from patients(age 57-96) confirmed to have AMI with chest pain(n = 48), unstable angina pectoris(n = 11), cardiac failure(n = 5), others with high creatine phosphokinase(CK) activity(n = 81) and renal failure(n = 28), by comparing among cTnT(qualitative and quantitative), H-FABP, CK and creatine phosphokinase isoenzyme MB(CK-MB) activity. The diagnostic validity of cTn was assessed by receiver operating characteristic(ROC) curve analysis. The cut off value for AMI of cTnI was 0.8 ng/ml, cTnT was 0.16 ng/ml and H-FABP was 19.0 ng/ml. The overall diagnostic sensitivity of cTnI was 83.1%, and 84.8% for cTnT (quantitative), 72.3% for cTnT(qualitative), 64.8% for H-FABP, 81.8% for CK and 59.3% for CK-MB. The overall diagnostic specificity of cTnI was 90.9%, and 81.3% for cTnT(quantitative), 60.5% for cTnT (qualitative), 53.2% for H-FABP, 52.9% for CK and 87.7% for CK-MB. The overall diagnostic efficiency of cTnI was 86.5%, and 82.7% for cTnT(quantitative), 63.6% for cTnT(qualitative), 59.8% for H-FABP, 69.0% for CK and 71.9% for CK-MB. False positive results for cTnI were found in a few cases with renal failure. cTnT(qualitative) showed false positive results in 22/28 with serum creatinine over 2.1 mg/dl due to renal failure. In conclusion, cTnI detection is considered a useful and sufficiently sensitive marker for AMI.     

A more appropriate cardiac troponin T level that can predict outcomes in end-stage renal disease patients with acute coronary syndrome

Purpose

Cardiac troponin T (cTnT), a useful marker for diagnosing acute myocardial infarction (AMI) in the general population, is significantly higher than the usual cut-off value in many end-stage renal disease (ESRD) patients without clinically apparent evidence of AMI. The aim of this study was to evaluate the clinical usefulness of cTnT in ESRD patients with acute coronary syndrome (ACS).

Materials and Methods

Two hundred eighty-four ESRD patients with ACS were enrolled between March 2002 and February 2008. These patients were followed until death or June 2009. Medical records were reviewed retrospectively. The cut-off value of cTnT for AMI was evaluated using a receiver operating characteristic (ROC) curve. We calculated Kaplan-Meier survival curves, and potential outcome predictors were determined by Cox proportional hazard analysis.

Results

AMIs were diagnosed in 40 patients (14.1%). The area under the curve was 0.98 in the ROC curve (p<0.001; 95% CI, 0.95-1.00). The summation of sensitivity and specificity was highest at the initial cTnT value of 0.35 ng/mL (sensitivity, 0.95; specificity, 0.97). Survival analysis showed a statistically significant difference in all-cause and cardiovascular mortalities for the group with an initial cTnT ≥0.35 ng/mL compared to the other groups. Initial serum cTnT concentration was an independent predictor for mortality.

Conclusion

Because ESRD patients with an initial cTnT concentration ≥0.35 ng/mL have a poor prognosis, it is suggested that urgent diagnosis and treatment be indicated in dialysis patients with ACS when the initial cTnT levels are ≥0.35 ng/mL.     

早期急性心肌梗死患者血清白细胞介素-1受体拮抗蛋白变化的临床价值

目的探讨血清白细胞介素-1受体拮抗蛋白（IL-1Ra）在早期诊断急性心肌梗死（AMI）患者中的临床价值。方法比较IL-1Ra、肌红蛋白（MYO）、肌钙蛋白I（cTnI）、肌酸激酶同功酶（CK-MB）四种物质定量检测对诊断发病6h内的AMI的敏感性、特异性和准确性。结果 AMI组IL-1Ra水平高于非急性心肌梗死组和正常对照组（P均〈0.01）;AMI组和非急性心肌梗死组患者血清IL-1Ra含量进行Logistic回归分析得知,IL-1Ra诊断AMI的最佳临界值为210pg/ml。IL-1Ra诊断发病3h和6h内的AMI的敏感性显著高于cTnI和CK-MB（P〈0.05）,特异性差异则无统计学意义（P〉0.05）,诊断准确性高于MYO、cTnI和CK-MB。结论 IL-1Ra在AMI患者中早期升高对发病〈3h的AMI患者有诊断意义,提示检测IL-1Ra可作为早期诊断AMI的一个重要的辅助指标。     

血清心肌型脂肪酸结合蛋白快速检测急性心肌梗死的敏感度和特异度分析

目的:分析血清心肌型脂肪酸结合蛋白(H-FABP)快速检测对急性心肌梗死(AMI)早期诊断的敏感度和特异度。方法:53例胸痛患者,经确诊分为AMI组(包括发病<6h和6～12h两亚组)和非AMI组,平行检测H-FABP、肌红蛋白(MYO)、心肌肌钙蛋白I(cTnI)、肌酸激酶同工酶(CK-MB),计算H-FABP等指标诊断AMI的敏感度和特异度。结果:H-FABP诊断发病<6h AMI的敏感度为85.71%,与MYO的80.95%相近,明显高于cTnI的47.62%和CK-MB的52.38%,差异有统计学意义(P<0.05);AMI发病6～12h,H-FABP诊断AMI的敏感度为100.00%,略高于MYO、cTnI和CK-MB(均为92.86%),但差异无统计学意义(P>0.05)。H-FABP等指标诊断AMI的特异度无论非AMI组还是健康对照组,各指标间差异均无统计学意义(P>0.05)。结论:H-FABP对AMI早期诊断有较高的敏感度和特异度,可作为AMI早期筛查及诊断指标。     

The determination of CK-MB protein mass]

It has been well known that the determination of CK-MB is a useful parameter for the diagnosis of acute myocardial infarction (AMI). Currently, several methods such as Electrophoresis, Ion-exchange chromatography, Immunoinhibition method and Protein mass determination are available. From a point of the diagnosis of AMI, the method should be satisfied with the requirements of high speed, ease to perform, high analytical specificity and high analytical sensitivity. However, there are no appropriate methods which can satisfy all of the requirement. In this paper, we have introduced the present situation concerning the determination of CK-MB in our hospital and discussed the results of study on the IMx method based on the determination of protein mass of CK-MB. We obtained good results in the fundamental study and found some advantages of protein mass determination. The first advantage was its high analytical specificity by use of monoclonal antibody. The second advantage was its high analytical sensitivity because of its low detection limit. The third advantage was the stability of sample because the antigenicity of CK-MB to the antibody of reagent is stable comparing with that of enzyme activity. From those advantages, the mass determination of CK-MB will be a useful method for the diagnosis of AMI in the near future.     

Clinical effectiveness of urinary human chorionic gonadotropin related protein (hCGRP) quantification for diagnosis of ectopic pregnancy

We detected pregnancy related new molecule, human chorionic gonadotropin related protein (hCGRP) in the urine of a pregnant women by using a monoclonal antibody against the human chorionic gonadotropin (hCG). This study examined the effectiveness of urinary hCGRP quantification in diagnosing ectopic pregnancy. This study included 40 normal pregnant women and 25 patients with ectopic pregnancy. Patients' serum and urinary intact whole hCG (i-hCG) and hCGRP concentrations were measured using sandwich ELISA and the ratio of hCGRP to i-hCG was calculated. Statistical analysis was performed using statistical package for social sciences (SPSS) 10.0. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the cut-off value to discriminate ectopic pregnancies from normal intrauterine pregnancies. Urinary hCGRP and hCGRP/i-hCG ratio in ectopic pregnancy group (14 +/- 6.6 ng/mL, 4.6 +/- 1.9%, respectively) were significantly lower than those of normal pregnancy group (149 +/- 10.2 ng/mL, 29.7 +/- 1.9%, respectively; p<0.001). Based on ROC curve analysis, a cut-off point of urinary hCGRP/i-hCG ratio <16.2% discriminated between ectopic pregnancy and normal pregnancy with a sensitivity, specificity, positive predictive value and negative predictive value of 92.0%, 90.0%, 32.6%, and 99.5%, respectively. Urinary hCGRP/i-hCG ratio measurement may be effective in diagnosing ectopic pregnancy.     

The validity of the Beck Depression Inventory-Short Form as a screening and diagnostic instrument for moderate and severe depression in medical inpatients

OBJECTIVE: To examine the concurrent validity of the Beck Depression Inventory-Short Form (BDI-SF) to detect moderate and severe depressive episodes according to the International Classification of Diseases, 10th edition (ICD-10) criteria in inpatients with heterogeneous medical conditions and to set cut-off scores for its use in medical wards. METHODS: One hundred and fifty-five patients [53% female; mean age (+/- S.D.) = 49.5 (+/- 17) years; mean number of years of education (+/- S.D.) = 6 (+/- 4) years] consecutively admitted to the adult medical wards in a General Hospital were interviewed during the first 72 h of hospitalization. The Clinical Interview Schedule [CIS] was used to make ICD-10 psychiatric diagnoses. All patients completed the BDI-SF. A "receiver operating characteristics" (ROC) curve was obtained and the sensitivity, specificity, positive and negative predictive values were calculated for different cut-off points of the BDI-SF. RESULTS: High sensitivity and negative predictive value (NPV) were obtained with a cut-off score of 9/10 (sensitivity = 100%, specificity = 83.1%, NPV = 100%). High sensitivity and positive predictive value (PPV) were obtained with a cut-off score of 13/14 (sensitivity = 93.5%, specificity = 96%, PPV = 85.3%). The area under the ROC curve was 98.4% (95% Confidence Interval = 0.97-1.00). CONCLUSIONS: The BDI-SF is a valid instrument for detecting moderate and severe depression in medical inpatients. For screening purposes, a 9/10 cut-off score is indicated, but if a high specificity is desired, a 13/14 cut-off score is warranted.     

血清心肌酶谱、肌钙蛋白Ⅰ、肌红蛋白与脑钠肽的联合检测对临床诊断急性心肌梗死的意义

目的 探讨急性心肌梗死(acute myocardial infarction,AMI)患者血清心肌酶谱(ASK、α-HBD、LDH、CK-MB、CK),肌钙蛋白Ⅰ (cTnⅠ),血浆脑钠肽(BNP),肌红蛋白(MYO)的水平变化,以探讨其对急性心血管疾病的临床诊断意义.方法 通过采用酶速率法检测75例急性心肌梗死患者的血清心肌酶谱,化学免疫发光定量分析法检测BNP、MYO、cTnⅠ,同时对单项测定和联合测定时诊断急性心血管疾病的灵敏度和特异性进行对照分析,揭示四者联合检测对急性心肌梗死的临床诊断意义.结果 急性心肌梗死患者组血清心肌酶谱,BNP,MYO,cTnⅠ的检测结果与健康对照组相比较差异均有统计学意义(P＜0.05);急性心肌梗死患者组血清心肌酶谱、BNP、MYO、cTnⅠ单项及四项联合检测的灵敏度分别为76.7％、86.7％、75.0％、83.3％、96.7％,特异性分别为80.0％、93.3％、66.7％、86.7％、93.3％;ROC曲线显示心肌酶谱、BNP、MYO、cTnⅠ单项及四项联合检测的曲线下面积(area under the curve,AUC)分别为0.812、0.904、0.772、0.773、0.963.结论血清心肌酶谱、BNP、MYO及cTnⅠ四项联合检测可提高急性心梗检测的灵敏度,有助于急性心梗的早期诊断.     

心肌肌钙蛋白在急性冠状动脉综合征诊断中的应用

为探讨心肌型肌酸激酶同工酶(CK-MB)与心肌肌钙蛋白T(cTnT)在诊断急性冠状动脉综合征(ACAS)时的相互关系,本文选择了157例疑似ACAS患者的血液标本,同时进行了CK-MB和cTnT的测定.结果表明:CK-MB与cTnT的相符率达82.1%(129/157).CK-MB对ACAS的敏感性为76.8%(43/56),特异性为78.2%(43/55);cTnT对ACAS的敏感性为94.6%(53/56),特异性为100%(43/43).cTnT与CK-MB在诊断ACAS的敏感性和特异性上,有显著差别(P《0.005).结论:cTnT取代CK-MB成为检测ACAS的新指标是可行的.     

Role of E-selectin for diagnosis of myocardial injury in children of age up to 14 years

Background: Effects of myocardial injury on E-selectin remain unclear. Thus, we investigated the diagnostic value of E-selectin for myocardial injury in children of no more than 14 years of age, which determined the scoring method of myocardial injury. Methods: In this prospective study, plasma E-selectin, cardiac troponin I (cTnI) and creatine kinase isoenzyme MB (CK-MB) concentrations in pediatric patients with myocardial injury (myocardial injury group, n=85) were measured. The control group comprised 80 patients without myocardial injury, and the case-control study method was selected at the same time. The definition of cardiac injury was based on cTnI and CK-MB (with or possibly without abnormal ECG evidence). Diagnostic value of E-selectin for myocardial injury was determined by analyzing receiver operating characteristic (ROC) curves. Results: The differences between the two groups were of statistical significance (P<0.001). For the 85 patients with myocardial injury, the area under the ROC curve (AUC) value for plasma E-selectin levels was 0.945 with a 95% CI of 0.899-0.991 and the optimal diagnostic cut-off value 29.67 ng/ml (positive likelihood ratio (positive LR=72.5); AUC value for plasma cTnI level was 0.848 with a 95% CI: 0.737-0.960 and the optimal diagnostic cut-off value was 0.155 µg/L (positive LR=12.3); AUC value for plasma CK-MB levels was 0.946 with a 95% CI: 0.903-0.989 and the optimal diagnostic cut-off value 24.26 IU/L (positive LR=72.5). Conclusions: E-selectin is more effective than cTnI in diagnosing myocardial injury as an important biological marker of myocardial injury- an important index of pediatric cardiac injury score.     

Evaluation of maternal plasma creatine kinase activity as a marker of abnormal early pregnancy

We have tested the value of maternal plasma creatine kinase activity for diagnosing ectopic pregnancies obtained after in-vitro fertilization and embryo transfer. Plasma creatine kinase was assayed in 57 patients: 20 normal, 23 miscarriages and 14 ectopic pregnancies, for a total of 240 samples. All values were in the lower part of the normal range except only one in a miscarrying patient. A statistically significant difference was observed for a cut-off value of 45 IU/l between normal and ectopic pregnancies. However, for this cut-off point, the measurement of plasma creatine kinase activity had a sensitivity of 0.50 and a specificity of 0.76 for the diagnosis of ectopic pregnancy. The positive predictive value was 0.69. Creatine kinase activity measurements are thus of no practical value in this particular population, in which an early and specific marker of ectopic implantation would be of paramount interest. The association of human chorionic gonadotrophin (HCG) determinations and ultrasound scanning of the pelvis still remain the best paraclinical support for an early diagnosis of ectopic implantation.      

Is adenosine deaminase in pleural fluid a useful marker for differentiating tuberculosis from lung cancer or mesothelioma in Japan, a country with intermediate incidence of tuberculosis?

The objective of this study was to evaluate the utility of the determination of adenosine deaminase (ADA) level in pleural fluid for the differential diagnosis between tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) in Japan, a country with intermediate incidence of tuberculosis (TB). We retrospectively reviewed the clinical records of 435 patients with pleural effusion and investigated their pleural ADA levels as determined by an auto analyzer. ROC analysis was also performed. The study included patients with MPE (n＝188), TPE (n＝124), benign nontuberculous pleural effusion (n＝94), and pleural effusion of unknown etiology (n＝29). The median ADA level in the TPE group was 70.8U/L, which was significantly higher than that in any other groups (p＜0.05). The area under the curve (AUC) in ROC analysis was 0.895. With a cut-off level for ADA of 36U/L, the sensitivity, specificity, positive predictive value, and negative predictive value were 85.5%, 86.5%, 69.7%, and 93.6%, respectively. As many as 9% of patients with lung cancer and 15% of those with mesothelioma were false-positive with this ADA cutoff setting. Although the ADA activity in pleural fluid can help in the diagnosis of TPE, it should be noted that some cases of lung cancer or mesothelioma show high ADA activity in geographical regions with intermediate incidence of TB, in contrast to high prevalence areas.     

传统心肌酶谱联合损伤相关蛋白IMA、TnI-Ultra检测对急性心肌梗死早期诊断的价值分析

目的 探讨肌酸激酶(CK)、肌酸激酶同功酶(CK-MB)、同型半胱氨酸(HCY)和乳酸脱氢酶(LDH)等心肌酶,联合血清缺血修饰清蛋白(IMA)和超敏肌钙蛋白I(TnI-Ultra)等心肌损伤相关蛋白检测在急性心肌梗死(acute myocardial infarction,AMI)早期诊断中的应用.方法 选取我院于2014年1月至2017年1月期间收治的AMI患者150例,病发后6h内采集静脉血,检测患者心肌酶谱(CK、CK-MB、HCY和LDH)及IMA和TnI-Ultra等生化指标.同期选取100例非AMI患者血液样本作为对照组.结果 150例AMI患者血清CK、CK-MB、LDH(U/L)和HCY(μmol/L)水平分别为:688.5±68.7、86.4±9.2、364.7±55.2和34.5±9.4.与对照组相比,CK和CK-MB水平明显升高(P<0.01),而LDH和HCY与对照组相比差异无统计学意义(P>0.05),但IMA(65.5±11.7 U/L)和TnI-Ultra(10.6±3.5μg/L)水平均明显升高,差异有统计学意义(P<0.01).结论 CK、CK-MB、HCY和LDH等心肌酶指标在AMI患者中有较高的阳性率,但某些非AMI类疾病也可能导致以上指标异常升高;IMA和TnI-Ultra等心肌损伤相关蛋白对AMI诊断有较高的特异性.心肌酶联合心肌损伤相关蛋白检测有助于AMI的早期诊断,对降低AMI风险具有重要意义.     

GP73与AFP联合检测在肝癌诊断中的应用价值

目的 通过检测HCC血清中的GP73和AFP含量,探讨GP73对于肝癌检测的应用价值.方法 通过ELISA方法对81例HCC、72例CH/LC和65例正常对照血清行GP73检测,并通过ROC曲线计算GP73诊断肝癌的敏感性和特异性.结果 HCC组、CH/LC组和正常对照组GP73含量分别为( 152.67±33.59) ng/ml、(93.15±20.02) ng/ml和(58.95±17.29) ng/ml.ROC曲线分析显示以120 ng/ml为Cut-off值,GP73诊断肝癌的敏感性为77.80％,特异性为78.00％.结论 GP73可以作为诊断肝癌的血清标志物,其敏感性好于AFP,同时通过联合检查可以提高肝癌的检出率,有一定的临床意义.     

Early diagnosis of acute myocardial infarction by an immunoinhibition method for analysis of creatine kinase isoforms

Conventional isoenzyme and enzyme values in serum usually are normal during the first few hours of acute myocardial infarction (AMI). Thus definitive diagnosis may be delayed. Measurement of serum creatine kinase (CK) isoform has begun to attract attention. In this study, we measured CK isoform with an immunoinhibition method in the first available samples from patients with AMI and from healthy subjects. In the 394 healthy subjects, the mean ratio of MM3 to MM1 of CK isoform was 0.494 +/- 0.1495 (SD). The upper limit of the reference values for this ratio was considered to be 0.793 (mean + 2 SD). In 40 of 48 patients, this ratio in the first available samples from patients with AMI was greater than 0.793. In 15 of 20 patients whose total CK activity was less than 260 IU/l, this ratio was greater than 0.793, while CK-MB activity measured with the immunoinhibition method was well within the reference range in all of these patients. Our results show that in the first available samples from patients with AMI, measurement of the ratio of MM3 to MM1 of CK isoform has the highest diagnostic efficiency. Thus, measurement of CK isoform with the immunoinhibition method can be applied for early diagnosis of AMI.