Adenosine deaminase activity (ADA) and CSF– protein was estimated in cerebrospinal fluid (CSF) of 1072suspected and diagnosed tubercular meningitis (TBM) patients.Clinically suspected TBMcases were 903 and 169 patients were diagnosed by combination of direct staining, culture methodand clinical evaluation.

Sensitivity and specificity of ADA levels in CSF to diagnose tubercular meningitis were 86.4% and 70% respectively at >5.6 IU/L cut off of ADA levels in CSF.Sensitivity and specificity of protein levels in CSF were 82.8% and 80.7%, respectively at > 100 mg/dL cut off of protein levels in CSF.The CSF–ADA level in TBM cases had significant positive correlation with CSF protein (p<0.001).CSF –glucose level was done as routine test and CSF –ADA was found negatively correlated with CSF glucose (p = 0.03).

Thus, determination of ADA activity and CSF– protein are reliable andvaluable adjunct in diagnosing tuberculous meningitis.