Adenosine deaminase activity in bronchoalveolar lavage in Turkish patients with smear negative pulmonary tuberculosis

The sputum smear-negative patients have been a diagnostic challenge for health professionals. Adenosine deaminase (ADA) activity has been shown to rise in various body fluids of patients with tuberculosis (Tb). A prospective clinical trial was conducted to determine the diagnostic value of ADA activity in bronchoalveolar lavage (BAL) in sputum smear-negative subjects highly suggestive for pulmonary Tb. Nineteen (M/F: 15/4, mean age 46.8 +/- 16.5 years) sputum smear-negative patients highly suggestive for pulmonary Tb constituted Group I. Acid fast bacilli (AFB) grew on sputum and/or BAL culture of all subjects in this group. Twenty-nine patients (M/F: 19/10, mean age 55.7 +/- 8.0 years) with non-tuberculous pulmonary diseases constituted Group II. Ten of them had interstitial lung disease, nine lung cancer, five pneumonia and five COPD. Twelve subjects (M/F: 7/5, mean age 48.4 +/- 12.8 years) constituted the controls (Group III) undergoing fiberoptic bronchoscopy (FOB) for various indications and the lungs were found to be normal eventually. Albumin and ADA activity levels were measured in plasma and BAL in all the subjects. LocalADA was calculated. PlasmaADA and BALADA of Group I was significantly higher (P < 0.001) than that of the other groups. LocalADA was also the highest in Group I when compared with the others (P < 0.001) but that of Group II was also higher (P < 0.01) when compared with controls. With a cut-off value derived from the control subjects, sensitivity of BALADA was 100% and specificity 85.3%. Sputum PCR results are available in a couple of days whereas that of BALADA are available in a couple of hours and BALADA costs cheaper than PCR in our country. Therefore, we conclude that BALADA may be a useful, cheaper and faster diagnostic test in sputum smear-negative patients highly suggestive for pulmonary Tb. LocalADA need not be calculated as it is also significantly higher in Group II subjects and thus not as reliable as BALADA.