DIFFERENTIAL-DIAGNOSIS OF PLEURAL EFFUSION BY LACTATE-DEHYDROGENASE ISOENZYME ANALYSIS

Study objective: To determine the diagnostic value of pleural fluid la ctate dehydrogenase (LDH) isoenzyme analysis in the differential diagn osis of pleural fluid. Patients and methods: Eighty-seven consecutive patients with pleural effusion caused by congestive heart failure (33) , infection (33), and malignancy (21) comprised a derivation set of pa tients. Pleural fluid LDH activity and isoenzyme pattern were establis hed in all patients and analyzed by the classification and regression trees (CART) method. An additional group of 20 consecutive patients co mprised a validation set that was used for cross-validation of CART-de rived decision tree. Results: A decision tree, with a positive predict ive value of 83%, was constructed and validated by data from a validat ion set of patients. Conclusions: Pleural fluid LDH isoenzyme pattern may be helpful for the differential diagnosis of the most common cause s of pleural effusions: congestive heart failure, infections, and mali gnancy.