Serum adenosine deaminase in pulmonary tuberculosis, malignancy and non-tubercular respiratory diseases.

The study has been conducted to find out the serum ADA levels in 120 patients with various pulmonary diseases which included patients with tubercular pleural effusion (n = 86), lung cancer (n = 10) and patients with non-tubercular pulmonary diseases like pneumonia, etc (n = 24). Twenty healthy individuals served as control subjects. The mean (+/- SD) of ADA activity was 23.38 (4.47), 7.29 (1.08), 12.71 (1.95) and 2.23 (1.00) units/litre in tuberculosis, malignancy, non-tubercular pulmonary diseases and healthy controls respectively with significant difference between each other (P less than 0.001). Patients with tuberculosis (100%) fall in 97% sensitivity range with a lower cut off limit at 17 units/litre ADA activity, while for malignancy and non-tubercular respiratory diseases, the sensitivity was 90% and 83% respectively. Within the sensitivity limits, the serum ADA activity can be used for the differential diagnosis of pulmonary diseases.