Role of Cerebrospinal Fluid Adenosine Deaminase in Diagnosis of Tubercular Meningitis in Adults

Abstract

BACKGROUND Tuberculous meningitis (TBM) still remains an important cause of morbidity and mortality in India. Due to lack of early and timely diagnosis of TBM, the fatality rate remains high. OBJECTIVES To evaluate the role of Adenosine Deaminase (ADA) activity in the Cerebrospinal Fluid (CSF) in diagnosis of Tubercular meningitis in adults. MATERIAL AND METHODS The study included 100 patients who presented with sign and symptoms suggestive of meningitis. All the patients were admitted; detailed history and examination including neurological examination was done. CSF samples were taken along with other routine investigations. CSF analysis was done for sugar, protein, cells, and ADA. X-Ray Chest was done in all patients to find out the lung involvement. RESULTS Out of a total of 100 patients, 49 were diagnosed as TBM based on the clinical features and CSF analysis. The CSF showed pleocytosis of 10 to 500 cells/mm3 predominantly lymphocytes, protein >45mg/dl, sugar<40mg/dl or <40% of blood glucose concentration. The mean ADA activity was 12.54±3.91 U/L in patients with TBM. The sensitivity and specificity was 75.51% and 100% respectively when a cutoff value of ADA of 10U/l was used, with an accuracy of 88%. CONCLUSIONS ADA activity in the CSF is very important and rapid screening test that can help in the diagnosis of TBM. ADA activity is markedly higher in TBM.