title: Reliability and significance of increased creatine kinase MB isoenzyme in the serum of uremic patients.
abstract: The authors quantified creatine kinase MB (CK-MB) isoenzyme activity and mass in the serum of 81 uremic and 20 nonuremic (control) patients who had no clinical or electrocardiographic evidence of acute myocardial infarction. CK-MB was quantified by three methods: electrophoresis, the QuiCK-MB (International Immunoassay Labs), and the Tandem-E CK-MB (Hybritech, Inc.). The authors then followed all uremic patients for subsequent hospitalization for cardiac disease. Median CK-MB was increased in the serum of the uremic patients as compared with the control patients by all methods. Most uremic patients had CK-MB in serum above the median CK-MB of the control group. Seventeen (21%) uremic patients had CK-MB in serum elevated above the reference range by at least one method. All control patients had CK-MB in the serum within the reference range. Twelve of 81 (15%) uremic patients have subsequently developed acute myocardial infarction (six patients; four died) or angina pectoris (six patients; one died). Eleven patients were specifically hospitalized for cardiac symptoms. One patient had acute myocardial infarction three weeks after renal transplant. With the use of the chi-square test and 2 X 2 contingency tables, patients with CK-MB in serum above 5 U/L by electrophoresis (chi 2 = 5.47; P less than 0.05) or at least 2.9 EU/L by the QuiCK-MB (chi 2 = 6.56; P less than 0.01) appeared to be at increased risk of subsequent hospitalization. The authors conclude that a slight increase of CK-MB in serum is found in most uremic patients. However, CK-MB elevated above reference range in the serum of uremic patients without clinical or electrocardiographic evidence of acute myocardial infarction is not common. When found, elevated CK-MB isoenzyme appears to be associated with an increased risk of subsequent cardiac disease. Therefore, quantification of CK-MB in the serum of uremic patients is more reliable than is implied in the literature.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000787:Angina Pectoris / Q000150:complications / Q000201:enzymology; D003402:Creatine Kinase / Q000097:blood*; D004586:Electrophoresis; D005260:Female; D006801:Humans; D007118:Immunoassay; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000201:enzymology; D012016:Reference Values; D014511:Uremia / Q000150:complications / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase