The evaluation of diagnostic value of serum Lactate dehydrogenase/pleural Adenosine deaminase ratio compared with pathology in diagnose of malignancy in exudative pleural effusion

Background: In recent studies, it has been somewhat determined that the Lactate dehydrogenase(LDH) ratio of serum to Adenosine deaminase(ADA)of pleural fluid has a diagnostic value in malignant pleural effusions. We decided to study the diagnostic value of these enzymes by conducting a wider study and a higher statistical society. Methods: This is a descriptive-analytic study that was conducted in a cross-sectional method. Sampling method was census and 39 patients with exudative pleural effusion were enrolled. Age, sex, biopsy report, serum LDH and ADA of pleural fluid were recorded in a preformed form. The LDH ratio of serum to ADA of pleural fluid was calculated. The collected data were entered into SPSS18, using statistical tests were analyzed. Results: Of the 39 patients,61.5% had cancer and 38.5% had infections. There was a significant relationship between mean pleural ADA and mean ratio of serum LDH to pleural ADA in terms of type of disease. The sensitivity, specificity, positive predictive value and negative predictive value of ratio of serum LDH level to pleural ADA level were 95.8%, 80%, 88.5% and 92.3%, respectively. Conclusions: Can be concluded that serum LDH/pleural ADA ratio are very consistent with pathological finding and can be used to diagnose of malignancy in exudative pleural effusion.