The Diagnostic Performance of Pleural Fluid Lactate Dehydrogenase to Adenosine Deaminase Ratio in Differentiating Infectious from Non-Infectious Pleural Effusions: A cross- sectional study
Diagnostic Utility of Pleural Fluid LDH/ADA Ratio
Keywords:
Pleural effusion, Diagnostic AccuracyAbstract
Abstract:
Objective: To determine the diagnostic performance of the pleural fluid lactate dehydrogenase to adenosine deaminase ratio in differentiating infectious from non-infectious pleural effusions.
Methods: This prospective analytical cross-sectional study was conducted at department of Pulmonology, Sahiwal Teaching Hospital, Pakistan, over six months. A total of 170 patients with pleural effusion were enrolled using a non-probability consecutive sampling technique. Adult patients with radiologically confirmed pleural effusion and pleural fluid adenosine deaminase levels >33 U/L were included. Infectious pleural effusions comprised tuberculous pleural effusion, parapneumonic pleural effusion and empyema, while non-infectious pleural effusions included malignant and transudative pleural effusions. Pleural fluid lactate dehydrogenase and adenosine deaminase levels were measured and the LDH/ADA ratio was calculated. Receiver Operating Characteristic curve analysis was performed to assess diagnostic performance.
Results: A total of 170 patients were included, with 128 (75.3%) classified as infectious and 42 (24.7%) as non-infectious pleural effusions. Infectious pleural effusions showed significantly higher pleural fluid lactate dehydrogenase, adenosine deaminase and LDH/ADA ratio values, whereas pleural fluid pH and glucose levels were significantly lower. The LDH/ADA ratio demonstrated excellent diagnostic performance with high sensitivity, specificity and overall diagnostic accuracy. An LDH/ADA ratio >10 was identified as the strongest independent predictor of infectious pleural effusion.
Conclusion: The pleural fluid LDH/ADA ratio is a simple, inexpensive and reliable biomarker for differentiating infectious from non-infectious pleural effusions and can serve as a valuable diagnostic tool in routine clinical practice.
