Validity of Adenosine Deaminase Levels in Cerebrospinal Fluid in Tuberculous Meningitis- A Study from North Bihar

Background: Incidence of Tubercular meningitis (TBM) in developing countries is 7-12%. About 25 % patients have poor prognosis because of delay in diagnosis. The aim of the present study is to find a simple, rapid, cost effective diagnostic test in differentiating tubercular etiology from other causes. Methods: Sixty-two patients admitted to our tertiary hospital with symptoms and signs of meningitis were selected and divided into two groups: tubercular (n=39) and pyogenic (n= 23), depending upon the accepted criteria. CSF examination done in each patients and adenosine deaminase (ADA) level estimated. Cut off value of ADA kept at or above 10 IU/L for tubercular meningitis. Results: The mean age of patients with tubercular meningitis was 39.07 ± 16.67 years and that of pyogenic meningitis 34.35 ± 16.73 years. Out of 39 tuberculous patients, 33 patients were found to be having CSF ADA at or above the cutoff value of 10 IU/L while six had below cutoff value. In tubercular meningitis, the ADA level in CSF ranged between 7 to 112 U/L with mean± SD as 35.72 ± 32.83 IU/L, while in pyogenic meningitis, the ADA level ranged between 2.4 to 7 IU/L with a mean ± SD as 4.21± 1.35 IU/L. On comparison between two groups, the CSF ADA level found to be statistically highly significant (P < 0.001). Conclusions: our study showed that estimation of ADA in CSF is not only simple, inexpensive and rapid but also fairly specific method for making a diagnosis of tuberculous meningitis. For this reason we recommend CSF ADA estimation in TBM.