Cerebrospinal fluid adenosine deaminase and its dynamic changes in tuberculous meningitis

Objective To explore the diagnostic value of cerebrospinal fluid (CSF) adenosine deaminase (ADA) level in tuberculous meningitis. Methods We retrospectively analyzed 139 patients (73 males, 66 females) who visited Beijing Chest Hospital for suspected TBM from January 2010 to June 2015. Of them, 99 patients were diagnosed to have TBM, with 45 males and 54 females, and a mean age of (33±15) years. Forty patients were diagnosed as having Non-TBM, with 28 males and 12 females, and a mean age of (35±18) years. All patients underwent lumbar puncture, and CSF ADA, routine, biochemical and bacteriological tests were performed. Thirty-five TBM patients reviewed CSF ADA test after treatment for 4 weeks, 8 weeks and 6 months. Results The level of CSF ADA in TBM group was higher than that in the non-TBM group, the difference being statistically significant (5.6 U/L vs 2.3 U/L, P=0.000). When the cut-off value of the CSF ADA was 3.8 U/L , the sensitivity and specificity for diagnosis of TBM were 60.6% (95%CI 50.3%-70.1%) and 87.5% (95%CI 72.4%-95.3%), respectively, and the area under the ROC curve was 0.734.The CSF ADA level was (6.7±4.2) U/L in the 35 cases of TBM before treatment. After 4 weeks, 8 weeks and 6 months of anti-tuberculosis treatment, the CSF ADA levels were (4.5±3.3) U/L, (3.7±2.7) U/L and (2.0±1.5) U/L, respectively; all significantly decreased as compared to that before treatment (P<0.001). There was no significant change in the ADA level between 8 weeks and 4 weeks (P=0.128). After 6 months of treatment, the level of CSF ADA was significantly lower than those after 4 and 8 weeks′ treatment (P<0.001). Conclusions CSF ADA in TBM patients was significantly higher than in non-TBM patients. The sensitivity of CSF ADA level in the diagnosis of TBM was poor, but the specificity was better. CSF ADA was significantly reduced and showed dynamic changes with effective anti-tuberculosis treatment and maybe helpful in evaluating the effect of treatment. Key words: Tuberculous meningieal; Adenosine deaminase; Cerebrospinal fluid