Diagnostic value of serum adenosine deaminase in tuberculous lymphadenitis

Background: Extra-pulmonary tuberculosis often requires FNAC or biopsy of lymph node to reach a final diagnosis of tuberculous lymphadenitis, which is invasive, expensive, and needs an advanced setting. Estimation of adenosine deaminase (ADA) in different body fluid and serum has been suggested as a quick, cheap, and reliable test for tuberculosis. Objective: The study was intended to assess the usefulness of serum ADA in the diagnosis of tuberculous lymphadenitis. Methods: This was a cross-sectional observational study, conducted in BSMMU over a two year period and included 68 participants, divided equally into two group e.g. tuberculous lymphadenitis and a healthy comparison group. As tuberculous lymphadenitis, only newly diagnosed cases, labeled on the basis of histopathological findings of epithelioid granuloma with caseation necrosis were included. Serum ADA concentrations were estimated by enzymatic method and compared between groups. Results: The mean serum ADA concentration was found to be 25.52±7.11 U/L in tuberculous lymphadenitis group, which was significantly higher (p=0.000) than that of the healthy comparison group (14.82±3.85 U/L). Three different cut-off values of serum ADA (18.25 U/L, 20.45 U/L, 22.15 U/L) were used to determine the best predictive value for the diagnosis of tuberculous lymphadenitis. Sensitivity and specificity of these cut off values were 91.2% and 82.4%, 79.4% and 88.2%, 67.6% and 97.1% respectively. Conclusion: It is clearly denoted by the study that, tuberculous lymphadenitis patients has significant higher serum ADA then the healthy comparison group. This result indicates that serum ADA can be used as a useful adjunct in the diagnosis of tuberculous lymphadenitis with conventional investigations. Bangladesh Med Res Counc Bull 2021; 47(2): 151-155