Lactate dehydrogenase isoenzymes in pleural effusions.

Abstract

Simultaneous pleural fluid and serum lactate dehydrogenase isoenzyme patterns in 90 patients with pleural effusions were studied to evaluate the efficacy of using these patterns to differentiate exudative effusions and to estimate the influence of serum lactate dehydrogenase on pleural fluid lactate dehydrogenase. Fourteen of 28 malignant effusions, but only 1 of 48 benign exudates, had pleural fluid lactate dehydrogenase2 greater than 35 per cent. The pleural fluid lactate dehydrogenase isoenzyme pattern for all benign exudates was similar and was characterized by a higher percentage of lactate dehydrogenase4 and lactate dehydrogenase5 in the pleural fluid than in the serum. Transudative pleural effusions had pleural fluid lactate dehydrogenase patterns similar to the serum patterns. The total pleural fluid lactate dehydrogenase and the lactate dehydrogenase isoenzyme patterns were not changed by the presence of blood in the pleural fluid.