INTRODUCTION:–This study was conducted to assess the usefulness of pleural fluid cholesterol in differentiating exudative from transudative effusion and as a diagnostic aid in patients with pleural effusion.

METHOD:– In this Descriptive  study we studied 100 cases with undiagnosed pleural effusion who were coming to OPD or IPD of Santokbha Durlabhji Memorial Hospital from July 2014 to March 2016. After cytological and biochemical  analysis of pleural aspirate sample, it was classified as transudative or exudative according to light’s criteria and final diagnosis with clinical diagnosis taken as gold standard for determining whether pleural effusion is exudative or transudative.Pleural cholesterol level was measured in all pleural fluid samples.

RESULTS:–In our study out of 100 patients 71 were exudative and 29 were transudative pleural effusion and included 68 male and 32 female patients with majority of the patients were in the age group of 21–30 years . most common etiological diagnosis for exudative effusion was tuberculosis(43% patients) followed by parapneumonic effusion(13% patients) and Malignancy (9% patients). In the transudative group, CHF (21% patients) was responsible for most of the cases. By using light’s criteria we were able to classify all of the 71 exudates correctly (sensitivity of 100%) but it misclassified 8 transudates (all had CHF) as exudative effusion (specificity of 72.41%).  After plotting ROC curves, the value of pleural fluid protein, pleural/serum protein ratio, pleural fluid LDH & Pleural/serum LDH ratio which could best differentiate exudative from transudative pleural effusion were ≥ 2.7 mg/dl(98.59% sensitivity, 96.55% specificity), ≥ 0.47(100% sensitivity, specificity), ≥396 IU/L ( 98.59% sensitivity, 86.21% specificity) & ≥0.555 (94.37% sensitivity, 89.66%specificity) . pleural fluid cholesterol level that would best differentiate exudative from transudative pleural effusion was found to be ≥53mg/dl (98.59%,sensitivity, 100%specificity ). Pleural fluid cholesterol level had maximum positive correlation with pleural fluid protein. On comparing the diagnostic efficiency of various parameters for diagnosing exudative pleural effusion, we observed that pleural/serum protein ratio was most efficient and Pleural fluid cholesterol had the second best accuracy.

CONCLUSION:–We concluded that  all the cases of transudative effusion which were misclassified by light’s criteria were correctly diagnosed using pleural cholesterol hence when used together could lead to lesser misclassification of effusions. Pleural fluid cholesterol is in itself an efficient independent variable for diagnosing pleural effusions and does not require simultaneous measurement of other parameters in serum as required for light’s criteria hence lowering the cost of diagnostic procedure.