[Measurement of adenosine deaminase activity in bronchoalveolar lavage fluids as a tool for diagnosing miliary...

Measurement of the activity of adenosine deaminase (ADA) in pleural effusions has been reported to be useful in the diagnosis of tuberculous pleuritis. To determine whether ADA activity can also be used to diagnose miliary tuberculosis, it was measured in bronchoalveolar lavage fluid from 64 subjects: 6 patients with miliary tuberculosis, 21 patients with sarcoidosis, 15 patients with idiopathic interstitial pneumonia, 15 patients with other diseases, and 7 healthy controls. Mean ADA activity was 5.02+/-3.75 IU/L (mean+/-SD) in patients with miliary tuberculosis; 1.06+/-0.99 IU/L in patients with sarcoidosis; 0.21+/-0.43 in patients with idiopathic interstitial pneumonia; and 0.30+/-0.51 IU/L in healthy controls. The level in patients with miliary tuberculosis differed significantly from the others (p<01.01). All 6 patients with miliary tuberculosis, 3 patients with sarcoidosis, 1 patient with Wegener's granulomatosis, and 1 patient with lymphangitic carcinomatosis had levels of ADA activity in bronchoalveolar lavage fluid that exceeded 2.0 IU/L. With a cut-off value of 2.0 IU/L the sensitivity of this test to miliary tuberculosis is higher than that of other diagnostic aids. Measurement of ADA activity in bronchoalveolar lavage fluid may be of great value in the early diagnosis of miliary tuberculosis.