Utility of Cerebrospinal Fluid Adenosine Deaminase and C-Reactive Protein in patients with Meningitis

Introduction: We aimed to assess the utility of cerebrospinal fluid (CSF) Adenosine deaminase (ADA) and C-reactive protein (CRP) in differentiating various types of meningitis in adult population. Materials and methods: The present observational study, conducted in the Department of Medicine, Lokmanya Tilak Municipal Medical College and Hospital from February 2016 till August 2017, included all meningitis and meningococcemia cases diagnosed according to the clinical and/or laboratory criteria during the study period were included in the study. Comparisons were made with respect to various biochemical investigations between patient groups diagnosed with various types of meningitis. Results: 38% were diagnosed as bacterial meningitis, 54% as tubercular meningitis and rest as viral meningitis. CSF ADA was significantly higher in tubercular meningitis as compared to bacterial or viral meningitis. Similarly, CSF CRP was found to be significantly higher among patients with bacterial meningitis. In tubercular meningitis, CSF ADA and CRP were not found to be significantly associated with CSF cell count, CSF protein or ratio of CSF/Blood glucose. In bacterial meningitis, CSF CRP was found to be significantly higher among patients with CSF protein between 101 to 200 mg/dl. Using a cut off value of 5 IU/L, CSF ADA was found to have a sensitivity of 100% and specificity of 91.3% in diagnosing tubercular meningitis and with cut off value of 9 mg/L, CSF CRP had a sensitivity of 97% and specificity of 100% in diagnosing bacterial meningitis. Conclusion: CSF ADA and CRP should be included in the workup of meningitis patients.