ABSTRACT
The study included 55 patients with pleural effusion [18 transudate, 27 bacterial empyema and 10 tuberculous exudate] their ages ranged from 1-10 years. Also 20 apparently healthy children of matched age and sex were taken as control. No significant difference was found in the levels of serum lysozyme between disease and control groups. There was a significant increase in pleural fluid lysozyme levels in bacterial empyema than in transudate or tuberculous exudates [P = 0.000, P = 0.001] respectively. There was also a significant increase in pleural fluid lysozyme in cases of tuberculous effusion when compared with transudate group [P = 0.002]. Pleural fluid-to-serum lysozyme [PL/SL] ratio was 0.81 +/- 0.11 mg/dL in cases of transudate, 11.69 +/- 2.48 mg/dL in bacterial empyema and 1.98 +/- 0.75 mg/dL in tuberculous effusion groups. The existence of a raised PL/SL ratio in cases of tuberculous and bacterial empyema groups suggested important local synthesis of lysozyme. Comparing patients of tuberculous effusion with patients of transudate a PL/SL ratio higher than 1.4 showed a sensitivity of 90%, specificity of 100%, positive predictive value of 100%, negative predictive value of 94.7% and accuracy of 96.4% for discrimination of tuberculous effusion. All of these suggest that the determination of pleural fluid lysozyme and PL/SL ratio is a simple, fast method for obtaining corroborative information in the differential diagnosis of tuberculous pleurisy from transudate