This is a descriptive study carried out in Khartoum state hospitals during the period from May 2012 to April 2014. The study aimed to evaluate the diagnostic role of the pleural effusion/serum (CHOL, LDH, and protein) ratios in the differentiation between exudate and transudate pleural effusion. As a part of the investigation, 135 serum and pleural effusion samples were collected from patients with accumulated plural effusion. Prior to testing, 5 mL of venous blood and 20 mL of pleural effusion samples were prepared in accordance with specific testing requirements. Exudative pleural effusions were observed in 95 (70.4%) samples, of which 64 (67.4%) belonged to male patients and 31 (32.6%) to females. The calculated means for CHOL, LDH, and protein levels in pleural effusion and serum samples between exudate and transudate effusion showed statistically significant differences with the p-value = 0.000. In distinguishing between exudative and transudate pleural effusion, a high Pearson correlation was observed between CHOL ratio and clinical diagnosis (r = 0.971), as well as between CHOL level in effusion samples and LDH level in serum samples (r = 0.867). Sensitivity, specificity, positive predictive value, and negative predictive value analysis of the parameters in the differentiation between exudate and transudate samples revealed the following values: 97.7% and 100%, 100%, and 95%, respectively, for the CHOL ratio; 86%, 97.4%, 97.4%, and 97%, respectively, for the LDH ratio; and 81.4%, 81.6%, 89.7%, and 70.4%, respectively, for the protein ratio. On the basis of the study findings, it could be concluded that estimation of CHO, LDH, and protein ratios can assist in the differentiation between exudative and transudate pleural effusion and thus patient management. Hence, this approach should be included in routine laboratory analyses of pleural effusions. Nevertheless, additional techniques should be incorporated in the diagnosis of doubtful pleural effusions, as this will improve the diagnostic sensitivity and specificity in this setting.
