Diagnostic significance of ascites adenosine deaminase levels in suspected tuberculous peritonitis in adults

Objective: There are contradictory reports about the use of adenosine deaminase (ADA) as a diagnostic marker in tuberculous peritonitis patients. Reports evaluating significance of ADA activity in the diagnosis of tuberculous peritonitis in adults are lacking in Nepal. We thus set out to investigate the ascitic fluid ADA levels in suspected tuberculous peritonitis patients and to determine the diagnostic significance of the test statistically. Methods: This study population comprised of two different adult patients groups. Group I 35 suspected cases of tuberculous peritonitis and Group II 35 cases of transudative ascites the control group (patients with biochemically proved transudates or hypoproteinaemia) and peritoneal tap was done. ADA estimation was carried out by spectrophotometry. Results: ADA levels (Mean ± SD) in suspected tuberculous peritonitis and transudative ascites cases were 48.5±17.9 U/L and 19.8±7.7 U/L respectively (P<0.001). In the receiver operating characteristic (ROC) curve for ascites, ADA cut-off level of 41.5 U/L was found to yield the best results of differential diagnosis; sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the test in tuberculous peritonitis cases were 80.0%, 97.2 %, 96.6%, 82.9%, 88.6% respectively. Conclusion: ADA levels are elevated in suspected tuberculous peritonitis cases and it is a simple, rapid, inexpensive and the least invasive test. It is thus a useful biochemical marker for the early diagnosis of tuberculous peritonitis while waiting for the results of mycobacterial cultures or biopsies. J Microbiol Infect Dis 2013; 3(3): 104-108