RAPID AUTOMATED-DETERMINATION OF ADENOSINE-DEAMINASE AND LYSOZYME FORDIFFERENTIATING TUBERCULOUS AND NONTUBERCULOUS PLEURAL EFFUSIONS

The catalytic concentration of pleural adenosine deaminase (ADA) and t he ratio of pleural lysozyme (PL) to serum lysozyme (SL) were measured in consecutive patients (49 tuberculous and 179 nontuberculous) with two automated procedures in a Hitachi 717 analyzer, Using sensitivity and specificity curves, we established cutoff values at 33 U/L for ADA and 1.7 for the PL/SL ratio, The sensitivity of ADA activities for tu berculous effusion was 90%, specificity 85%, Combining ADA with the PL /SL ratio enhanced specificity to 99%. However, high values for ADA an d lysozyme ratios are not, alone or in combination, sensitive or speci fic enough to replace pleural biopsy or culture of pleural fluid for t he diagnosis of tuberculous empyema.