Adenosine deaminase isoenzymes estimation - as a diagnostic tool for tuberculous pleural effusions

Objective:To assess the efficacy of ADA isoenzyme estimation over that of total ADA level in pleural fluid and serum as a more efficient diagnostic indicator in tuberculous pleural effusions in high prevalence country like India.Methods:The efficacy was analysed in total thirty four patients of pleural effusions.Total ADA was estimated by Guitsi and Galanti Calorimetric method and ADA isoenzymes with and without EHNA[Erythro-9-(2- hydroxy-3-nonyl) adenine]a potent ADA1inhibitor using the same method.Results:The results demonstrated a statistically significant values of ADA2in serum(P<0.001),pleural fluid(P = 0.000) and significant value for the ratio of pleural fluid ADA2/serum ADA2(P<0.001) and pleural fluid ADA/ADA(2(P<0. 005).The sensitivity and specificity values of pleural fluid ADA|2 is 81.8%and 91.6%(cut off value 60 IU/L for Tuberculous effusions),serum ADA295.4%and 66%(cut off value 70 IU/L for tuberculous effusions). ADA2is an isoenzyme,which is significantly raised in tuberculous pleural effusions both in the serum and pleural fluid.Conclusion:Estimation of ADA isoenzymes is redundant as a diagnostic aid over total ADA estimation in view of the limited improvements both in specificity and sensitivity patterns and also in term of cost-benefit ratio.