PLEURAL FLUID TO SERUM-CHOLINESTERASE RAT IO TO DISCRIMINATE BETWEEN TRANSUDATES AND EXUDATES - REEVALUATION IN 177 PATIENTS

Background and objectives. In a previous study we concluded that the p leural fluid/serum (PF/S) ratio of cholinesterase was the most useful parameter to discriminate between exudates and transudates, The object ive of the present study was to confirm these findings in a prospectiv e series of patients with pleural effusion. Material and methods. A to tal of 177 patients, consecutively studied at two institutions, with t he diagnosis of pleural effusion were included in this study, Thirty-s ix (20.3%) effusion were transudates and 141 (79.7%) exudates; of thes e, 73 and 68 were of malignant and benign origin, respectively. Both P F/S cholinesterase and Light's criteria were compared. Results, The PF /S cholinesterase ratio incorrectly classified 12 pleural effusions (6 .8%), These included 7 out the 36 transudates (19.4%) and 5 out of the 141 exudates (3.5%), the latter of malignant etiology, Following Ligh t's criteria, four (2.2%) exudates were misclassified, all of them tra nsudates, The higher accuracy of Light's criteria was statistically si gnificant (p = 0.04). Conclusions. In this series of patients, Light's criteria were more accurate than PF/S cholinesterase ratio to discrim inate between transudates and exudates, From these results, the use of the PE/S cholinesterase ratio parameter is no longer recommended.