Evaluation of cerebrospinal fluid adenosine deaminase levels as an ancillary diagnostic test for tuberculous meningitis and its correlation with adverse neurological outcome

Background : Tuberculous meningitis (TBM) is often under and over diagnosed, thereby making the ancillary diagnostic tests important for establishing the diagnosis of TBM. The objective of this study was to evaluate cerebrospinal fluid adenosine deaminase (CSF-ADA) as an ancillary test for the diagnosis of TBM, and further, its correlation with adverse neurological outcome in these patients. Materials and Methods : This was a prospective study of 83 patients. The diagnosis of TBM was established by Thwaites criteria. CSF-ADA levels were measured in all these patients and were taken to be positive at levels >10 IU/l. These patients were followed up at 1 and 3 months after discharge, and the resultant neurological deficit was measured as per the modified Rankin score and correlated with the initial CSF-ADA levels. Mann-Whitney U test, χ2 test, Kruskall-Wallis tests were used for statistical analyses. Results : CSF-ADA values were higher than 10 IU/l in all the 83 patients diagnosed to be suffering from TBM. It was seen that the mean ADA level for patients with stage I/II was 18.23 ± 8.64 IU/l, while it was 31.97 ± 226 004, India.