Mair J
Institut für Medizinische Chemie and Biochemie, University of Innsbruck, Austria.
Clin Chim Acta. 1997 Jan 3;257(1):99-115. doi: 10.1016/s0009-8981(96)06436-4.
Creatine kinase (CK) MB and lactate dehydrogenase (LDH) isoenzyme 1 are not heart-specific. By contrast, the regulatory proteins troponin I and troponin T are expressed in three different isoforms, one for slow-twitch skeletal muscle fibers, one for fast-twitch skeletal muscle fibers, and one for cardiac muscle (cTnI, cTnT). cTnI and cTnT are usually not detectable in patients without myocardial damage, which is a prerequisite for high diagnostic performance. After acute myocardial infarction (AMI) cTnI, cTnT, and CKMB mass have a comparable early sensitivity. cTnI and cTnT usually peak in parallel except for patients without reperfusion in whom cTnI peaks about 1 day and cTnT approximately 3-4 days after onset of AMI. Both stay increased for at least 4-5 days. cTnT tends to stay increased longer than cTnI. Because the sensitivities of cTnI and cTnT for myocardial injury are comparable, their specificities are the main topic of current debate. Recent reports on mismatches of cTnI and cTnT in patients with renal failure and myopathy without other evidence for myocardial injury suggest that cTnT could be reexpressed similar to CKMB and LDH-1 in chronically damaged human skeletal muscle. In contrast to cTnT, CKMB, and LDH-1, cTnI is not expressed in skeletal muscle during fetal development. So far, an increase in cTnI has been reported only after myocardial damage. Because of currently higher costs, troponin measurement should be restricted at present to clinical settings that really require their high specificity. Based on its distinct functional association with the metabolism of acute ischemic myocardium and according to initial clinical results, glycogen phosphorylase isoenzyme BB is a promising enzyme for the early detection of ischemic myocardial damage.
肌酸激酶（CK）同工酶MB和乳酸脱氢酶（LDH）同工酶1并非心脏特异性的。相比之下，调节蛋白肌钙蛋白I和肌钙蛋白T以三种不同的同工型表达，一种用于慢肌纤维，一种用于快肌纤维，另一种用于心肌（cTnI、cTnT）。在没有心肌损伤的患者中通常检测不到cTnI和cTnT，这是高诊断性能的一个前提条件。急性心肌梗死（AMI）后，cTnI、cTnT和CKMB质量具有相当的早期敏感性。cTnI和cTnT通常同时达到峰值，但在没有再灌注的患者中除外，这些患者的cTnI在AMI发作后约1天达到峰值，cTnT在大约3 - 4天达到峰值。两者至少会升高4 - 5天。cTnT升高的持续时间往往比cTnI长。由于cTnI和cTnT对心肌损伤的敏感性相当，它们的特异性是当前争论的主要话题。最近关于肾衰竭和肌病患者中cTnI和cTnT不匹配且无其他心肌损伤证据的报道表明，cTnT可能会像CKMB和LDH - 1一样在慢性受损的人类骨骼肌中重新表达。与cTnT、CKMB和LDH - 1不同，cTnI在胎儿发育期间不在骨骼肌中表达。到目前为止，仅在心肌损伤后报道了cTnI升高。由于目前成本较高，目前肌钙蛋白检测应仅限于真正需要其高特异性的临床情况。基于其与急性缺血心肌代谢的独特功能关联以及根据初步临床结果，糖原磷酸化酶同工酶BB是早期检测缺血性心肌损伤的一种有前景的酶。
