Study of cholesterol activity in pleural effusion

Abstract

Background: Pleural effusions are collections of fluid in pleural cavities and areactually manifestations of diverse diseases both infective and non infective and alsocardio-pulmonary in origin or extra-pulmonary. Based on the pathology of formationthe fluid can be either transudate or exudate. The most commonly accepted criteriaof differentiation is the Light’s criteria published by Richard Light in 1972 wherepleural fluid protein and lactate dehydrogenase enzyme were estimated along withtheir respective level in serum and necessary calculation were done. In1987 Hammet.al suggested that estimation of pleural fluid cholesterol too reliably can differentiateas the cholesterol level increases in infective and malignancy like pleural fluid proteinand it is low in transudates. The present study was done to estimate pleural fluidcholesterol in infective, malignant and other non infective cases in our setup and tostudy its accuracy in differentiation.Aims & objective: to study pleural fluid cholesterol level and to study its accuracyin differentiation of exudates verses transudates and to study correlation of pleuralfluid cholesterol with serum cholesterol and pleural fluid proteinMethodology: There were 100 cases of pleural effusions and 75 were due to infectiveand malignant cases and rest were transudative. Fluids were aspirated and analysedaccordingly. Pleural fluid protein and pleural fluid cholesterol both were estimatedalong with their levels in serum. American society of clinical pathologist laid downvalue of pleural fluid cholesterol54mg/dl & ratio of pleural fluid cholesterol/serumchlosterol0.3 as exudates. Further correlation in between cholesterol and protein levelin pleural fluid were studied and also serum cholesterol and pleural fluid cholesterol.Results achieved were analysed statistically. A P0.05 was considered as statisticallysignificant.Results & observation: With a cut of value of pleural fluid cholesterol 54mg/dlall malignant and parapneumonic cases were classified as exudates. Among the 57tubercular cases 52 cases were classified as exudate and among the 25 transudate cases24 are successfully dedifferentiated. So the misclassification rate is 6% with accuracyof 94%; the sensitivity achieved is 98.5% & specificity82.7%. When the ratio of pleuralfluid cholesterol/serum cholesterol is used as the differentiating marker misclassifiedrate is 5% & accuracy 95%.The sensitivity is 98.6% & specificity 85.7%. The study ofcorrelation reveals that there is a strong positive correlation in between pleural fluidprotein and pleural fluid cholesterol in both exudate and transudate and the resultbeing statistically significant (P0.05).Discussion: In this study pleural fluid cholesterol level and its ratio with serumcholesterol were used as differentiating parameter for classifying exudate and transudatein 100 cases of pleural effusion in our setup and compared with studies of Lightet.al and Hamm et.al . We got similar accuracy of differentiation like the pioneer studyin separation of serous fluid i.e. Light’s criteria. The study of correlation also signifiesthat in infective causes and malignancy pleural cholesterol increases as pleural fluidprotein and decreases in transudate and this is statistically significant.Conclusion: To overcome few fallacies of Light’s criteria there was a search for newparameters in pleural fluid for better differentiation and cholesterol was used in thisregard. In our study pleural fluid cholesterol and its ratio with serum cholesterol canreliably be used as differentiating parameter and in our results the misclassificationrate was 5% with accuracy of 95%