FREQUENCY OF TUBERCULOSIS IN EXUDATIVE LYMPHOCYTIC PLEURAL EFFUSION

Abstract

Background: Tuberculosis (TB) remains a major cause of exudative lymphocytic pleural effusion in high-burden countries, including Pakistan. Tuberculous pleuritis is diagnostically challenging and requires integration of clinical, laboratory, and microbiological findings. Objective: To determine the prevalence of TB among patients with exudative lymphocytic pleural effusion and evaluate the diagnostic performance of adenosine deaminase (ADA) levels, lymphocyte percentage, lactate dehydrogenase (LDH) ratio, and protein/serum protein ratio. Methodology: A cross-sectional observational study was conducted at Northwest General Hospital, Peshawar, from November 2025 to February 2026, including 167 patients with exudative lymphocytic pleural effusion. Demographic, clinical, and laboratory data were collected. Tuberculous pleural effusion was defined using a composite reference standard based on microbiological and/or histopathological confirmation. Diagnostic performance of pleural fluid parameters was assessed, and Fisher’s exact test and multivariable logistic regression were used for analysis. Results: Among 167 patients, 79 (47.3%) had tuberculous pleural effusion. ADA showed 84.8% sensitivity, 21.6% specificity, and 51.5% accuracy. Lymphocyte percentage demonstrated 100% sensitivity but 2.3% specificity. LDH/serum ratio and protein/serum ratio showed high sensitivity but limited specificity. Comorbidities were significantly associated with TB (p=0.031) and independently predicted TB (adjusted OR=2.87; p=0.034). Microbiological confirmation included culture (29.1%), GeneXpert MTB/RIF (35.4%), and Ziehl-Neelsen staining (11.4%); caseating granulomas were identified in 44.3% of biopsied patients. Conclusion: Tuberculosis was a frequent cause of lymphocytic exudative pleural effusion in this study population. Pleural fluid parameters provide supportive information but have limited specificity and should be interpreted with microbiological and histopathological findings. Further multicenter studies are required for validation.