Role of serum adenosine deaminase (ADA) in the diagnosis of tuberculosis & other respiratory diseases

Abstract

: The WHO Tuberculosis (TB) statistics for India in 2021 gave an estimated incidence figure of 25,90,000 cases, i.e., about 40% of Indian population is infected with TB. There are different investigative methods available for TB diagnosis like ZN-staining of ., which lacks sensitivity & another method of Mycobacterial culture takes around 6-8 weeks to isolate . in culture which results in delayed diagnosis & treatment and meanwhile further progression of disease. Other sensitive methods like PCR & CBNAAT are costly & they require skilled personnel & lots of equipment. Therefore, there is a need of simple, cost-effective, rapid & reliable test which can be easily carried out in the clinical laboratories of resource limited countries. In some previous studies, the level of ADA in effusion fluids was used for the diagnosis of TB, but it is not always possible to access effusion fluid & it requires skilled personnel. Thus, the aim of the present study is to evaluate the usefulness of measuring the serum level of ADA as noninvasive biochemical marker in early diagnosis of TB.The present cross-sectional study was conducted on 200 serum ADA samples. Patient samples were divided into four groups based on their diagnosis, i.e., 50 patients with pulmonary TB, 50 patients with extra-pulmonary TB, 50 patients with respiratory infections other than TB & 50 healthy people not having TB. The ADA level for each group was presented as mean + SD & compared by applying post hoc Bonferroni test which showed that the pulmonary TB group was significantly different from the other 3 groups with p<0.001. According to ROC curve analysis, the best cutoff point was 21.8 IU/L at which sensitivity & specificity were 88% & 87% respectively.Serum ADA activity with high sensitivity & specificity percentage can be used as a reliable marker in the diagnosis of TB & to differentiate TB from other respiratory illness.