Adenosine Deaminase (ADA)

The Adenosine Deaminase (ADA) test is a specialized biochemical assay primarily used to detect tuberculous pleurisy or tuberculosis (TB) in extrapulmonary fluids. ADA is an enzyme involved in purine metabolism, and its levels rise significantly when the body cellular immune system is activated—specifically during the proliferation of T-lymphocytes.

While a blood test for ADA is possible, it is most commonly performed on fluids collected from body cavities, such as pleural fluid (around the lungs), peritoneal fluid (abdomen), or cerebrospinal fluid (CSF). A high concentration of ADA in these fluids serves as a sensitive biomarker, suggesting that the body is fighting an infection like TB.