Usefulness of csf-ada as an ancillary tool in the diagnosis of tbm

Introduction: Tuberculous meningitis (TBM) is a global health issue and is the most severe form of extrapulmonary tuberculosis with high mortality and morbidity. Even after many years of experience with the disease, the definitive diagnosis of TBM remains a problem. Adenosine Deaminase enzyme is produced by lymphocytes and monocytes and reflects cell-mediated immunity. The enzyme is estimated easily by the colorimetric method. Generally, ADA assays may be useful in confirming TBM, but raised levels may also be seen in other CNS disorders (sarcoidosis, meningeal lymphoma, subarachnoid hemorrhage, neurobrucellosis), rendering it too nonspecific.
Aim: To evaluate the role CSF-ADA in the diagnosis of tuberculous meningitis as an ancillary tool.
Materials and Methods: The study was a prospective study, done in the department of medicine and department of neurology from September 2015 to August 2016. The patients who got admitted with the clinical picture of Meningitis in Medicine and Neurology department were assessed on Thwarts Criteria and those found to be likely cases of T.B.M, as per the criteria were included in the study and their CSF-ADA levels were measured.
Results: CSF ADA levels ranged from 8 to 251 units with a mean value of 32.97±40.863 and median of 20.40. ADA levels of patients with Thwaite’s score -3 to 0 were significantly lower (19.20±14.41) as compared to those of patients with Thwaite’s score -5 (43.54±50.54). Statistically, this difference was significant too (p=0.003).
Conclusion: CSF ADA levels were found to be above 10 IU/L in 86 patients enrolled and presumptively diagnosed as TBM based on the Thwaite’s criteria. Thus the sensitivity was found to be 86.9 %, suggesting its importance as an ancillary tool for the diagnosis of TBM.