Lactate dehydrogenase isoenzyme analysis for the diagnosis of pleural effusion in haemato-oncological patients

This study aimed to evaluate the utility of the pleural fluid lactate dehyd rogenase (LDH) isoenzyme algorithm for the differential diagnosis of pleura l fluid in patients with haematological malignancies. Twenty consecutive haemato-oncological patients with pleural effusion, hosp italized in the Haematology Department during a 2.75-year period, were pros pectively and independently evaluated for the cause of effusion by standard methods and the LDH isoenzyme algorithm. The causes of the pleural effusio ns established during the standard evaluations were compared to the results obtained from the LDH isoenzyme algorithm. Following the standard evaluation, the pleural effusion was attributed to c ongestive heart failure in one patient, to infection in six, to the underly ing malignancy in 12 and to concomitant congestive heart failure and malign ancy in one. LDH isoenzyme analysis correctly predicted the cause of pleura l effusion in 18 patients (positive predictive value 90%). In haemato-oncological patients, the pleural fluid LDH isoenzyme pattern ma y be helpful in the differential diagnosis of the most common causes of ple ural effusion.