Raised Adenosine Deaminase in Cerebrospinal Fluid: A Diagnostic Marker of Tuberculous Meningitis

Background: Tuberculous meningitis (TBM) is an important and common central nervous system (CNS) infection, particularly in developing countries with high mortality rate. More accurate and rapid diagnostic tests are necessary to prevent delays in specific treatment and to prevent sequelae. Objective of the study was using Adenosine Deaminase (ADA) levels in CSF as rapid screening tests to differentiate various types of meningitis. Methods: The study was conducted in patients with signs and symptoms of meningitis of varied etiology. Diagnosis was made by appropriate and relevant investigations and patients were categorised in different groups, depending upon the accepted criteria. CSF-ADA estimation was done by spectrophotometer. Results: According to the accepted criteria 30 patients (52%) having fulfilled the criteria were labeled as tubercular, while the other 28 (48%) were labeled as non-tubercular. Mean CSF ADA levels in tuberculous meningitis groups was significantly higher as compared to pyogenic meningitis and viral meningitis. Our study results indicate that ADA level estimation in CSF not only helps in the diagnosis of TBM, CSF ADA level 10U/L as a cutoff value exhibited 96.66% sensitivity, 100% specificity and 100% positive predictive value in differentiating tuberculous from non-tuberculous meningitis. Conclusion: CSF-ADA level is a simple and reliable test in differentiating TBM from other types of meningitis.