Abstract

Objective: Adenosine deaminase (ADA) is the catalysing enzyme for the deamination of adnosine to inosine. CSF ADA is thought to be released by T lymphocytes during cell mediated immune response such as tuberculous meningitis. We studied CSF ADA level in various meningitis patients.
Methods
We assayed the activity of ADA in the CSF of 162 patients with various types of meningitis from May 2008 through May 2012 at Daegu Catholic University Hospital. All patients were received CSF study involving ADA level and brain imaging. The patients were separated into tuberculous meningitis, non-tuberculous meningitis and aseptic meningitis groups.
Result
Numbers of tuberculous meningitis, non-tuberculous meningitis and aseptic meningitis patients were 17, 28 and 117. Mean values of ADA level in tuberculous meningitis, non-tuberculous meningitis and aseptic meningitis were 12.26±4.41 IU/L, 9.43±16.9 IU/L, and 3.26±2.91 IU/L. The CSF ADA was very high in 2 patients of severe non-tuberculous meningitis (61 and 77 IU/L). The cut-off values of CSF ADA level for diagnosing tuberculous meningitis was 10 IU/L. The mean ADA value in CSF was higher in tuberculous meningitis than in other meningitis. The sensitivity of the test for diagnosing tuberculous meningitis was 0.82 and specificity, 0.97. Increased CSF protein in tuberculous meningitis (175.17±61.9 mg/dL) showed in relative linearity with ADA activity in CSF (p<0.05).
Conclusions
We thought that CSF ADA level may help in early diagnosis of tuberculous meningitis. However, sometimes higher ADA level can observed in severe bacterial meningitis.