Adenosine deaminase activity and its isoenzymes in the sputum of patients with pulmonary tuberculosis
Abstract:BACKGROUND: Adenosine deaminase (ADA) has been widely used for the diagnosis of tuberculous pleural effusion. Two isoenzymes have been described, ADA1 and ADA2.
OBJECTIVE: To evaluate the diagnostic value of sputum ADA, ADA1 and ADA2 activity in pulmonary tuberculosis (TB).
DESIGN: We measured total ADA, ADA1 and ADA2 activity in the sputum of 27 patients with pulmonary TB (11 had a negative Ziehl-Neelsen stain for acid-fast bacilli [AFB]). Nineteen patients with lung cancer were used as controls.
RESULTS: Sputum total ADA activity was significantly higher in TB than in lung cancer patients (median 18 U/l [range 3–70] vs. 6 U/l [2–16]; P < 0.001). Sputum ADA2 activity was significantly higher in TB compared to lung cancer patients (9 U/l [0–65] vs. 5 U/l [0–12]; P = 0.001). Sputum ADA2 was significantly higher than ADA1 in TB patients (P = 0.001). Sputum ADA and ADA2 were higher in both AFB-positive and AFB-negative TB patients. Using a cut-off level of respectively 16 UI/l and 5UI/l for sputum total ADA and ADA2, sensitivity and specificity were 55.6% and 100% for total ADA and 81.5% and 63.2% for ADA2.
CONCLUSION: Sputum total ADA and ADA2 levels are elevated in patients with pulmonary TB. As they are elevated even in AFB-negative patients, they may assist in the early diagnosis of pulmonary TB.
Document Type: Regular Paper
Publication date: June 1, 2009
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