Diagnostic value of adenosine deaminase in nontuberculous lymphocytic pleural effusions.
Adenosine deaminase (ADA) can aid in the diagnosis of tuberculous pleural effusions, but false-positive findings from lymphocytic effusions have been reported. The purpose of this study is to assess the ADA levels in nontuberculous lymphocytic pleural effusions (lymphocyte count > 50%) of different aetiologies. Altogether, 410 nontuberculous lymphocytic pleural fluid samples were consecutively selected. These included malignant effusions (n = 221), idiopathic effusions (n = 76), parapneumonic effusions (n = 35), postcoronary artery bypass graft surgery effusions (n = 6), miscellaneous exudative effusions (n = 21) and transudative effusions (n = 51). The ADA level reached the diagnostic cut-off for tuberculosis (40 U x L(-1)) in seven of the 410 cases (1.71%). The negative predictive value of ADA for the diagnosis of pleural tuberculosis was 99% (403 of 407 cases) in the group of lymphocytic pleural effusions. In five of these seven patients ADA1 and ADA2 were measured, and in all these cases (100%) ADA1/ADA(p) correctly classified these lymphocytic effusions as nontuberculous (ratio < 0.42). This prospective study provides additional evidence that adenosine deaminase levels in nontuberculous lymphocytic pleural effusions seldom exceed the cut-off set for tuberculous effusions. The pleural fluid adenosine deaminase levels were significantly higher in different types of exudative effusions than in transudates. An adenosine deaminase level < 40 IU x L(-1) virtually excluded a diagnosis of tuberculosis in lymphocytic pleural effusions. Adenosine deaminase1/adenosine deaminase(p) correctly classified all nontuberculous lymphocytic pleural effusions with high adenosine deaminase levels.
Jiménez Castro
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Emergency Dept, Ramón y Cajal Hospital, Madrid, Spain. djc_69_98@yahoo.com
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Pérez-Rodríguez
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D000243:Adenosine Deaminase / Q000032:analysis*; D003937:Diagnosis, Differential; D006801:Humans; D018655:Lymphocyte Count; D008214:Lymphocytes / Q000473:pathology*; D010996:Pleural Effusion / Q000175:diagnosis* / Q000201:enzymology / Q000473:pathology*; D011446:Prospective Studies; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000201:enzymology
D000243:Adenosine Deaminase