Pleural fluid MDA and serum-effusion albumin gradient in pleural effusion

Pleural fluid malondialdehyde (PMDA) and serum effusion albumin gradient(SEAG) were estimated in 60 patients of pleural effusion of diverse etiologies. The results were compared with Light's criteria to distinguish between transudates and exudates. The mean PMDA level was 0.68±0.24nmol/ml and 1.17±0.25nmol/ml in transudates and exudates respectively showing a statistically significant (p<0.05) rise in exudates in comparison to transudates. SEAG registered a significant fall in exudates (P<0.001) when compared with transudates. PMDA revealed a positive correlation with pleural protein(r=+0.30) and a significant negative association with SEAG (r= -0.33).Sensitivity and specificity of PMDA were better than the parameters of Light's criteria. Whereas SEAG documented approximately equal sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with Light's criteria. Therefore PMDA and SEAG can be taken together in addition to Light's criteria to strengthen the discrimination between transudates and exudates in borderline cases of pleural effusion.