Razi Journal of Medical Sciences

 The first step in diagnosing the cause of effusion is to differentiate exudate from transudate. In according to that, Light’s criteria has been used for years, but sometimes the amount of protein and LDH of the pleural effusion remains at the borderline, therefore detecting other components may be useful.

  This research is a cross-sectional study with a sample of 70 patients having pleural effusion, the levels of LDH, bilirubin, cholestrol and protein in the pleural fluid and serum were measured. Light’s criteria also was used as “gold standard”. The cholestrol level above than 60 mg/dl and the ratio of cholestrol and of pleural fluid to that of serum above than 0.3 and 0.6 respectively were considered to be the characteristics of an exudate. In the analysis of the results, specificity, sensitivity, positive and negative predictive value, positive and negative likelihood ratio and accuracy were used.

  The sensitivity and the specificity of the ratio of bilirubin in the pleural effusion to serum was measured to be 5.4% and 69.2% respectively, for pleural cholesterol as 81.5% and 66.6%, for the ratio of pleural cholestrol to serum as 87.2% and 68.6%, PPV as 87.2%, NPV as 68.4%, PLR as 2.75 and NLR as 0.18.

  Thoroughly, the results of the ratio of Pleural cholestrol to that serum and pleural cholestrol, proned to have more diagnostic values than the bilirubin level in differentiating exudate from transudate.