Adenosine Deaminase (ADA) (Pleural Fluid)

Adenosine Deaminase (ADA) is an enzyme involved in purine metabolism and is a marker of cell-mediated immunity, particularly T-lymphocyte activation. Measuring ADA levels in pleural fluid is a widely accepted and reliable supportive test for diagnosing tuberculous pleural effusion, especially in TB-endemic regions.

Elevated ADA levels in pleural fluid strongly suggest tuberculosis as the cause of pleural effusion, helping differentiate it from malignancy, bacterial infections, or transudative effusions due to cardiac or renal disease. The test is rapid, cost-effective, and is usually interpreted along with clinical features, chest imaging, microbiological studies, and pleural fluid cytology for accurate diagnosis.