Diagnostic and prognostic utility of serum adenosine deaminase in tuberculosis: Worth a revisit or are we flogging a dead horse?

Background Measurement of adenosine deaminase (ADA) activity in body fluids is one of the biochemical methods for the diagnosis of tuberculosis (TB). While the role of ADA levels in pleural fluid and cerebrospinal fluid for diagnosis of TB has been established, the role of serum ADA is yet to be established. Aims To study the role of serum ADA levels in diagnosis and prognosis of TB. Settings and Design This prospective observational study was carried out at a hospital in central India. All TB patients managed at the center in 2021 were included in the study. Materials and Methods Two hundred and thirty-three TB patients who met the inclusion criteria were recruited for the study. The subjects were divided into various study groups on the basis of TB subtypes. The study subjects were treated with first-line DOTS antitubercular therapy (ATT). The subjects underwent analysis of serum ADA levels at 0, 2, and 5 months of ATT initiation. Various factors affecting serum ADA levels were studied. Results There was no statistically significant difference in mean serum ADA levels among all study groups (I–IV) at month 0 (treatment initiation). The mean serum ADA levels of TB patients in all study groups (17.8 ± 5.1) were significantly higher than in the control group (10.1 ± 1.2). Mean serum ADA levels showed a sustained fall from month 0 to month 5 of treatment in all study groups. Low vitamin D levels (below 20 ng/mL), Mantoux negativity, and sputum smear status were not found to affect serum ADA levels. Conclusion Serum ADA levels can be used to evaluate response to ATT and for disease prognostication.