THE STUDY OF PLEURAL FLUID LACTATE DEHYDROGENASE /ADENOSINE DEAMINASE RATIO TO DIFFERENTIATE BETWEEN TUBERCULOUS AND PARA PNEUMONIC PLEURAL EFFUSION

Abstract

Background: Pleural Effusion is a commonly observed clinical manifestation which is associated with more than 50 recognized diseases and disorders. Pleural uid lactate dehydrogenase (LDH) and adenosine deaminase (ADA) levels are often used to distinguish between tuberculous pleural effusion (TPE) and para pneumonic pleural effusion (PPE). This is challenging as the LDH level varies from normal to severely increased in PPE and a signicantly elevated ADA is frequently measured in both conditions. In this study, we evaluated use of the pleural uid LDH/ADA. Material and Methods:This was a prospective observational case study. this study included 51 cases more than 18 years of age; presenting with unilateral pleural effusion meeting criteria of exudative pleural effusion to the OPD & IPD of Department of Medicine and Department Pulmonary Medicine S.R.N. Hospital Prayagraj, U.P. Following allotment, Pleural uid aspiration was done, and patients were divided into 2 groups: tubercular and parapneumonic pathology. Pleural uid sent for analysis (cytology, microbiology, and biochemistry). Pleural uid LDH and ADA levels and LDH/ADA ratios were compared between two groups and results were obtained. Results: out of 51 study subjects , 27 were diagnosed to have Tubercular pleural effusion and 24 were found to have parapneumonic pleural effusion .The median pleural uid LDH,ADA and LDH/ADA ratio in TPE group were found to be 293.8 U/L ,59.8 U/L & 6.1 where as in PPE group it was found to be 503.3 U/L , 12.6 U/L and 40.Using LDH/ADA ratio as indicator of TPE an area under the ROC curve of 0.998 was obtained at cutoff value of 16.465.The sensitivity ,specicity , positive predictive value and negative predictive value was found to be 96.4%,100%,100% and 95.8%. Conclusion: The pleural uid LDH/ADA ratio at cut-off level of 16.465 is highly effective in differentiating between TPE and PPE and can be used as a useful diagnostic aid for the clinicians and thus improving patient care.