肌酸激酶同工酶质量判定肌病心肌损害的局限性

目的 通过对比小儿心肌炎、肌病时血清中肌酸激酶同工酶(CK-MB)质量与肌钙蛋白I(cTnI)和肌红蛋白(Mb)的动态变化,观察CK-MB质量在判定心肌损伤中的意义.方法 测定40例心肌炎患儿(其中有20例为暴发性心肌炎)和38例肌病患儿的肌酸激酶(CK)、CK-MB活性、CK-MB质量、cTnI、Mb、心电图以及脉冲多普勒超声心动图;肌病组同时进行肌电图、遗传代谢病筛查以及基因检测.以同期本院发育儿科门诊除外甲状腺功能减低症的10例身矮待查儿童为对照.结果 ①健康对照组儿童CK(U/L)为95.0±27.0,CK-MB活性(U/L)为22.6±1.3,CK-MB质量(μg/L)为2.4±0.3,cTnI(μg/L)为0.012±0.001.②心肌炎组患儿治疗前CK(1 033.0±408.0)、CK-MB活性(101.2±31.5)、CK-MB质量(38.2±13.2)、cTnI(5.544±1.554)均较健康对照组明显升高(均P＜0.01);随着治疗时间延长,各项指标逐渐下降;治疗2周后CK(59.3±25.1)、CK-MB活性(24.6±13.2)、CK-MB质量(3.3±2.9)、cTnI(0.125±0.128)均恢复至正常水平(均P＞0.05).治疗1周后CK、CK-MB质量增高率即较治疗前明显下降CK:5.9％(1/17)比56.4％(22/39);CK-MB质量:8.3％(1/12)比61.1％(22/36),均P＜0.01],CK-MB质量恢复先于cTnI,增高率出现明显差异8.3％(1/12)比73.7％(14/19),P＜0.05].③肌病组治疗前CK(10 193.0±1 447.0)、CK-MB活性(311.7±44.4)以及CK-MB质量(229.2±47.9)均较健康对照组明显升高(均P＜0.01),但cTnI不高(0.021±0.002);治疗2周后CK(5 735.6±6 187.8)、CK-MB活性(170.7±143.0)、CK-MB质量(207.4±136.6)仍维持在高水平,cTnI(0.230±0.150)则维持在正常水平;各项指标的增高率与治疗前均无显著差异CK:85.7％(6/7)比97.4％(37/38); CK-MB活性:85.7％(6/7)比97.4％(37/38);CK-MB质量:100.0％(2/2)比94.1％(32/34);cTnI:0(0/1)比6.4％(2/31),均P＞0.05].结论 ①在心肌炎时,CK-MB质量与cTnI一致,急性期升高,恢复期降至正常,但CK-MB质量观察窗短于cTnI.②在肌病时,CK-MB质量与cTnI 分离,前者治疗前后均升高,后者正常,故用测定CK-MB质量来判定肌病患儿是否有心肌损害意义有限.

The limitation of MB isoenzyme of creatine kinase mass in assess myocardial injury with muscular disease

Objective To examine the changes in serum MB isoenzyme of creatine kinase mass (CK-MB mass),cardiac troponin I(cTnI),and myoglobulin(Mb)in children with myocarditis and muscular disease in order to evaluate the significance of index CK-MB mass for the diagnosis of myocardium injury in these diseases.Methods Blood samples were collected from 40 children with myocarditis,38 children with muscular diseases,and 10 healthy children,for the measurement of creatine kinase(CK),CK-MB activity,CK-MB mass,cTnI,and Mb.Myocarditis patients also received electrocardiogram and pulse Doppler electrocardiogram examination while muscular diseases patients were subjected to electro-myographic examination,inherit-metabolic diseases screening and related gene analysis.The data were analyzed for differences between groups,and differences between values before and after the treatment.Results In comparison with healthy controlsCK(U/L):95.0 ± 27.0,CK-MB activity(U/L):22.6 ± 1.3,CK-MB mass(μg/L):2.4±0.3,cTnI(fig/L):0.012±0.001],the patients with myocarditis had significantly(all P＜0.01)higher mean values in CK(1 033.0± 408.0),CK-MB activity(101.2± 31.5),CK-MB mass (38.2± 13.2)and cTnI(5.544±1.554)before the treatment.After 2 weeks of treatment these indexes returned to the level of controls,with cTnI responded the last(CK:59.3±25.1,CK-MB activity:24.6± 13.2,CK-MB mass:3.3±2.9,cTnI:0.125±0.128).One week after treatment,the incidences of CK and CK-MB mass elevation were significantly lower than the values before the treatmentCK:5.9 ％(1/17)vs.56.4％(22/39); CK-MBmass:8.3％(1/12)vs.61.1％(22/36),both P＜0.01],with the change in CK-MB mass appeared significantly earlier than cTnI8.3％(1/12)vs.73.7％(14/19),P＜0.05].The patients with muscular disease also had significantly elevated mean value in CK(10 193.0± 1 447.0),CK-MB activity(311.7 ± 44.4),and CK-MB mass(229.2 ± 47.9)in comparison with healthy controls before the treatment(all P＜0.01).But their cTnI(0.021±0.002)was not significantly different from the control at this time.Two weeks after treatment,the elevated indexes were still significantly higher than the control(CK:5 735.6±6 187.8,CK-MB activity:170.7±143.0,CK-MB mass:207.4±136.6),while the level of cTnI(0.230±0.150)remained at the level of the control group.The incidence of index elevation was not significantly different from the values before the treatment for all the indexes testedCK:85.7％(6/7)vs.97.4％(37/38); CK-MB activity:85.7％(6/7)vs.97.4％(37/38); CK-MB mass:100.0％(2/2)vs.94.1％(32/34); cTnI:0(0/1)vs.6.4％(2/31),all P＞0.05].Conclusions In patients with myocarditis,CK-MB mass and cTnI both follow a consistent pattern of change:elevated in the acute stage of the disease but return to normal after recovery.In patients with muscular diseases,these 2 indexes have different pattern of change.CK-MB mass is significantly higher than control even after the treatment,while cTnI value remain unchanged.Therefore,CK-MB mass has very limited value as an index for myocardial injury in these patients.