Diagnostic Evaluation of Adenosine Deaminase (ADA) Test in the Early Diagnosis of Tuberculous Meningitis

Jigna KD,Saklainhaider SM,Pranay KS,Parthesh KJ,Navin IS,Kairavi JD

doi:10.5530/ijmedph.2.2011.3

Abstract

Objective: Tuberculous meningitis (TB M) is the commonest form of neurotuberculosis caused by Mycobacterium tuberculosis bacilli (MTB). The diagnosis of TBM is often difficult. A reliable, cost effective and rapid diagnostic test, which can be performed in any routine laboratory, could be of help in the diagnosis of TBM. In the present study we measured the adenosine deaminase (ADA) activity in cerebrospinal fluid (CSF) of TBM and non-TBM patients. Method: ADA activity in CSF was determined according to a method based on the modified Berthlot reaction, which is the formation of a colour indophenol complex from ammonia liberated from adenosine, and quantified spectrophotometrically. Results: ADA activity was studied in CSF of 45 cases of tuberculous meningitis, 20 cases of pyogenic meningitis and 20 controls (patients without any neurological disorders who were given spinal anaesthesia). The mean ADA activity was 13.43 ± 4.76, 8.23 ± 2.91 and 2.64 ± 1.57 IU/L in tuberculous meningitis, pyogenic meningitis and controls respectively. The higher level of ADA in tuberculous meningitis was statistically significant (p < 0.0001). The sensitivity and specificity of ADA test in CSF at cut-off 10 U/L was 100% and 93.75% respectively. Conclusion: This study demonstrated that adenosine deaminase activity in CSF, a relatively inexpensive and easy procedure, can be of great value in the diagnosis of tuberculous meningitis. This test can be performed in any routine laboratory where more sophisticated methods are not available.

Highlights

Tuberculosis (TB) is one of the leading causes of mortality and morbidity in developing countries
The adenosine deaminase (ADA) activity was estimated in 85 cases which include 45 Tuberculous meningitis (TBM) patients, 20 pyogenic meningitis and 20 control cases
Most developing countries have the dubious distinction of having higher prevalence and incidence of tuberculosis and lack of well equipped laboratory services for proper diagnosis of tubercular meningitis

Summary

Introduction

Tuberculosis (TB) is one of the leading causes of mortality and morbidity in developing countries. The World Health Organization Reports put to the record that globally, approximately 16 millions people are suffering from active TB with an estimated 8.5 million developing active TB each year, resulting in approximately 2 million deaths.[1] Tuberculous meningitis (TBM) is an endemic disease among socioeconomically disadvantaged communities in both developing and developed countries.[2] In India, nearly 5 lakh people die due to tuberculosis each year. The importance of this disease has increased since there is emergence of acquired immuno-deficiency syndrome (AIDS) and multidrug resistant TB.[4]

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Conclusion