Cardiac troponin, CK-MB and myoglobin for the early detection of acute myocardial infarction and monitoring of reperfusion following thrombolytic therapy

It is important to establish as soon as possible whether patients who present with chest pain are having an acute myocardial infarction (AMI). Ideally, sensitive and specific serum myocardial markers could provide the basis for early detection as well as determine the status of reperfusion following thrombolytic therapy. The present study examined the utility of cardiac troponin I (cTnI), CK-MB, and myoglobin for the sensitive and specific detection of AMI in 98 consecutive patients presenting to the emergency department (ED) with chest pain. In addition, cardiac troponin T (cTnT), CK-MB, and myoglobin samples were measured over a 90 min time period following thrombolytic therapy in nine separate AMI patients to assess reperfusion. In the ED study, CK-MB, myoglobin, and cTnI were equally sensitive (100%) for the detection of AMI in patients who presented 7.4-14 h after onset of chest pain. However, cTnI was the most specific serum marker (specificity 91.9% compared to CK-MB 85.6%, myoglobin 61.4%). Five of the six non-related AMI patients who had an elevated cTnI had clinically documented myocardial involvement. In the reperfusion study, cTnT, CK-MB and myoglobin, relative increases were greater in reperfused compared to non-reperfused patients. Within the reperfused group, the relative increase of cTnT was greater than CK-MB and myoglobin at 90 min following thrombolytic therapy. These findings show the clinical utility of cardiac-specific troponins as markers for the early detection of AMI and monitoring of reperfusion following thrombolytic therapy.

Lipase and pancreatic amylase activities in tissues and in patients with hyperamylasemia

Lipase, pancreatic amylase, and total amylase activities were measured in nondiseased and diseased human pancreatic tissues and in six different locations of the human digestive system. In addition, it was determined whether serum lipase and pancreatic amylase tests could replace the total amylase test to improved diagnostic efficiency in the evaluation of acute pancreatitis in hyperamylasemia patients. Nondiseased pancreatic tissue contained 4.5 times more lipase activity than total amylase activity. Diseased pancreatic tissue contained less activity for both lipase and total amylase compared to normal tissue. The total amylase activity of the pancreas was comprised solely of pancreatic amylase. Tissue obtained from six different anatomic locations in the digestive system contained 35 to 45 times less lipase and total amylase activity compared to the pancreas. Total amylase activity of the digestive system tissues were comprised of 25% pancreatic and 75% salivary isoamylases. Lipase, pancreatic amylase, and total amylase levels also were determined in serial serum samples from 17 consecutive hyperamylasemia patients admitted with possible acute pancreatitis. The serum lipase level remained higher than normal longer than either the total amylase and pancreatic amylase levels. In patients with hyperamylasemia of pancreatic origin, a poor correlation was observed at admission between serum pancreatic amylase and serum lipase. Not all patients with elevated lipase had an elevated pancreatic amylase level and vice versa. However, in every patient pancreatic disease would have been detected by the elevation of either lipase or pancreatic amylase levels. Diagnostic efficiency for pancreatic disease using serum pancreatic amylase, lipase, and total amylase tests was 94.1%, 76.5%, and 64.7%, respectively. These data suggest that lipase and pancreatic amylase tests are specific for the pancreas and might be considered replacements for total amylase as the stat or routine laboratory test for the diagnosis of pancreatic tissue injury.

Clinical and analytical evaluation of two immunoassays for direct measurement of creatine kinase MB with monoclonal anti-CK-MB antibodies

We examined the clinical and analytical performance of two immunoassays (Becton Dickinson CK-MB; Ciba-Corning Magic Lite CK-MB) in which monoclonal anti-CK-MB antibodies are used for directly measuring creatine kinase (EC 2.7.3.2) isoenzyme MB (CK-MB) in serum, and also one electrophoretic method (Ciba-Corning). Within- and between-assay precision for both immunoassays was good at the upper reference limits (less than 10% CV). Analytical recoveries ranged from 102 to 114%. Both immunoassays were free from interference by CK-BB, mitochondrial-CK, macro-CK, adenylate kinase, and CK-MM. Retrospectively, we evaluated four categories of patients, using both immunoassays and electrophoresis: normal controls, acute myocardial infarction (AMI) patients, severe skeletal muscle trauma patients, and acutely ill patients known not to have AMI. In general, there were excellent correlations among all three methods. CK-MB activity (U/L) measured by the Becton Dickinson immunoassay was approximately 50% of the mass concentration (microgram/L) of the Magic Lite immunoassay and 50% of the activity concentration (U/L) determined by electrophoresis. Both immunoassays were easy to perform and sensitive to the low CK-MB concentrations often found with low total-CK activities.