Sputum adenosine deaminase activity in patients with pulmonary tuberculosis and lung cancer

Objectives. The aim was to evaluate sputum adenosine deaminase (ADA) activity in patients suffering from pulmonary tuberculosis (TB) compared with patients with lung cancer and elucidate the possible applicability of ADA activity in patients with a negative acid-fast bacilli (AFB) smear. Material and Methods. Sputum samples were collected from 34 patients with pulmonary TB (21 with positive and 13 with negative AFB smear) and 33 patients with lung cancer. The samples were diluted 1 : 6 and homogenized with phosphate buffer (70 mM, 0.5 Mmol NaCl, pH = 6) and, after centrifugation, ADA was determined in the supernatant by the Giusti method. Results. The mean ADA value in the TB group was 18.29 IU/l +/- 15.76 and in the lung cancer group 11.25 IU/l +/- 8.38 (p = 0.026). ADA activity in the TB AFB-positive group was 16.57 IU/l +/- 13.23 and in the TBC AFB-negative group 20.31 IU/l +/- 15.89 (p = ns.). Conclusions. Patients suffering from pulmonary TB have higher sputum ADA activity than patients with lung cancer. Sputum ADA activity may be a useful tool for the diagnosis of pulmonary TB, especially in the detection of active AFB smear-negative TB cases.