title: Usefulness of various lactate dehydrogenase isoenzyme 1 profiles after myocardial infarction.
abstract: Isoenzyme profiles of lactate dehydrogenase (percent LD-1 of total LD, LD-1/LD-2 ratio, and absolute LD-1) have all been studied as late markers for myocardial infarction. It is known, however, that elevations of LD-5 frequently occur in this period as a result of liver congestion. Elevations of LD-5 may also occur as a result of complicating conditions. Such elevations could result in a reduced percent LD-1 of total LD, giving rise to false negatives. Receiver operating characteristic (ROC) curves were constructed for LD-1, LD-1/LD-2 and percent LD-1 of total LD from 285 specimens (124 patients) with suspected myocardial infarction. There was little difference in overall diagnostic power among the three assays. Using cutoffs determined from the ROC curves, 6 patients (18 specimens) were evaluated who appeared to be in the late period or who exhibited complicating conditions which could increase LD-5. In 14/18 specimens, increases in LD-5 resulted in false negatives by percent LD-1 of total LD. Only 5/18 specimens were false negatives by LD-1 or LD-1/LD-2. It is concluded that the percent LD-1 of total LD was affected by an increase in LD-5, and caution is recommended when using it.
authors.affiliation: Department of Pathology, University of Louisville, KY.
authors.forename: S S
authors.initials: SS
authors.lastname: Levinson
authors.forename: G A
authors.initials: GA
authors.lastname: Hobbs
mesh_terms: D003402:Creatine Kinase / Q000097:blood; D004586:Electrophoresis; D005189:False Positive Reactions; D006801:Humans; D007120:Immunochemistry; D007527:Isoenzymes / Q000097:blood*; D007770:L-Lactate Dehydrogenase / Q000097:blood*; D009203:Myocardial Infarction / Q000201:enzymology*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase