Relationship of Pleural and Serum Cholesterol and Lipoprotein Levels in Exudative and Transudative Effusions

This study aimed to assess whether total cholesterol (CHOL), low-density lipoprotein cholesterol (LDL), and high-density lipoprotein (HDL) are sensitive markers for discriminating between transudative and exudative pleural effusions (PE). In this study CHOL, LDL, HDL, TG, protein and LDH were analyzed in PE and serums of 119 patients with pleural effusion out of which 49 had transudative and 70 had exudative pleural effusion. Sensitivity, specificity, and area under the curve (AUC) of CHOL, LDL and HDL were measured by receiver operating characteristic curve (ROC). Pleural fluid CHOL, LDL and HDL levels were significantly lower in the transudate group compared to the exudate (29.6 ±16.3 mg/dl versus 65.24 ± 25.9 mg/dl, p<0.001; 17 ±14.8 mg/dl versus 43.94 ± 21.6 mg/dl, p<0.001; and 9.2 ± 4.8 mg/dl versus14.9 ± 6.3 mg/dl, p<0.001, respectively). Sixty-seven percent of cases with pleural transudates were secondary to heart failure, while 41% and 39% of those with pleural exudates were of parapneumonic effusion and neoplastic origin, respectively. Pleural fluid CHOL, LDL and HDL levels were significantly higher in malignant pleural effusion (71.5±18.6, 48.1±17.4 and 16.1±6.6mg/dl, respectively), and in parapneumonic effusion (70.7±28.5, 49.4±22.4 and 14.7±6.4 mg/dl, respectively) than in heart failure (30.6±11.9, 17.5±10.4 and 9.6 ±5.4 mg/dl, respectively). The optimum cut-off value for pleural fluid CHOL level of ≥38 mg/dL had a sensitivity of 87% and 80% specificity, for LDL pleural fluid level a cut-off value of ≥ 22.5 mg/dl had a sensitivity of 87% and 78% specificity, and for HDL pleural fluid a cut-off value of ≥ 10.5 mg/dl had a sensitivity of 70% and 69% specificity. AUC values were 0.906, 0.883, and 0.783, for CHOL, LDL, and HDL of pleural fluid, respectively. We conclude that pleural fluid CHOL, LDL and HDL are significantly increased in exudative effusions compared to the transudative ones. Measurement of CHOL, LDL and HDL concentrations in pleural effusions is useful in distinguishing exudates from