Pleural Fluid Adenosine Deaminase as a Biochemical Indicator in Diagnosing Tuberculous Pleural Effusion in Patients from Sudan

Background: The determination of optimal adenosine deaminase (ADA) levels for diagnosing TPE has been extensively researched. The study aimed to establish local diagnostic cutoff values for ADA in pleural fluid (pfADA) to evaluate TPE and enhance its utility. Methods: A cross-sectional study was conducted involving 60 patients with TPE who were referred to the Tropical Diseases Teaching Hospital in Khartoum State from December 2021 to March 2022. Demographic and clinical data were gathered. The pfADA was estimated using spectrophotometric methods, in conjunction with a pleural biopsy performed at the same site. The cutoff value of pfADA was established through the analysis of the receiver operating characteristic (ROC) curve. Results: Of 60 patients enrolled, 42 (70%) tested positive for pfADA; within this group, 34 (81%) exhibited positive tuberculosis granuloma in the biopsy. The optimal pfADA diagnostic cutoff value was 29 U/L, with sensitivity, specificity, positive predictive value (PPV), negative predictive value, and area under the curve (AUC) reported as 94.4%, 66.7%, 78.1%, 92.3%, and 0.806, respectively. Compared to pfADA-negative patients, pfADA-positive patients showed significantly elevated levels of albumin >3.5 g/dl (88.1% vs. 11.1%; p = 0.033), LDH >1000 U/L (42.6% vs. 22.2%; p = 0.001), lymphocytosis (80% vs. 50%; p = 0.042), and neutropenia (20% vs. 50%; p = 0.049). Conclusion: This is the first study to establish a local pfADA cut-off of 29.0 U/L for identifying TPE within the studied population.