Evaluation of Cerebrospinal Fluid Adenosine Deaminase Activity for the Differential Diagnosis of Tuberculous and Nontuberculous Meningitis

Abstract

IntroductionThe diagnosis value of adenosine deaminase (ADA) activity in cerebrospinal fluid (CSF) of tuberculous meningitis (TBM) has been well documented. However, the cutoff point of CSF ADA has not been fully assessed. In the current study, the authors set to calculate the cutoff points of ADA and monitor the changes of CSF ADA activities in patients with TBM after antitubercular therapy. MethodsCSF ADA activity in patients with different types of meningitis was measured by Trinder enzyme-coupled assay. ResultsThe mean CSF ADA values in the patients with TBM, bacterial meningitis, viral meningitis, cryptococcal meningitis and noninfectious neurologic disorders were 14.1 ± 5.4, 9.6 ± 5.5, 4.3 ± 2.5, 7.8 ± 3.4 and 2.6 ± 1.3 U/L, respectively. CSF ADA activity was significantly higher in TBM compared with patients with non-TBM (P < 0.05). Moreover, the best cutoff point for differentiating between TBM and non-TBM was 9.5 U/L. In addition, CSF ADA activity was decreased in patients with TBM after antitubercular therapy in a time-dependent manner. ConclusionsThe determination of ADA with a cutoff value of 9.5 U/L in CSF is a useful aid for the differential diagnosis of TBM and non-TBM. Moreover, dynamic monitoring of CSF ADA activity may be an indicator for evaluating antitubercular therapy in TBM.