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Pleural fluid myeloperoxidase as a marker of infectious pleural effusions
J Alegre1, J Jufresa, C Alemán
1Serveis de Medicina Interna, Bioquímica i Medicina Preventiva y Epidemiologia, Hospital General Universitari Vall d'Hebron 119-129, 08035, Barcelona, Spain
Abstract:
Background: The aim of this study was to establish the diagnostic accuracy of neutrophil markers (elastase, lysozyme, myeloperoxidase) found in pleural fluid in differentiating between infectious and non-infectious pleural effusions (PE). Methods: We studied 184 patients over 18 years of age with PE, classified as either infectious (34 complicated parapneumonic, 32 non-complicated parapneumonic, 45 tuberculous) or non-infectious (31 neoplasms and 42 undiagnosed exudates). Polymorphonuclear elastase (PMN-E) was determined using an immunoactivation method and lysozyme using a turbidimetric method. Myeloperoxidase (MPO) was measured by double antibody competitive radioimmunoassay. Receiver operating characteristic (ROC) curves were used to evaluate diagnostic accuracy. Results: Pleural fluid MPO was the biochemical marker that best differentiated between infectious and non-infectious PE. The ROC area under the curve (AUC) for myeloperoxidase was 0.86. MPO values over 550 &mgr;g/l diagnosed infectious PE with a specificity of 90.4% and a sensitivity of 77.4%. After excluding purulent parapneumonic PE, the sensitivity of a pleural MPO value >/=550 &mgr;g/l was 72.6%. Conclusions: Pleural fluid MPO was the marker that best differentiated between infectious and non-infectious PE.
Insights
Pleural fluid myeloperoxidase (MPO) effectively distinguishes infectious from non-infectious pleural effusions. This neutrophil marker demonstrated high diagnostic accuracy, aiding in differentiating PE causes.
Area of Science:
- Pulmonary Medicine
- Clinical Chemistry
- Diagnostic Immunology
Background:
- Pleural effusions (PE) require accurate differentiation between infectious and non-infectious etiologies.
- Neutrophil markers in pleural fluid are potential diagnostic tools.
Purpose of the Study:
- To assess the diagnostic accuracy of neutrophil markers, including elastase, lysozyme, and myeloperoxidase (MPO), in pleural fluid for differentiating infectious from non-infectious PE.
Main Methods:
- 184 patients with PE were analyzed.
- Pleural fluid samples were tested for polymorphonuclear elastase (PMN-E), lysozyme, and myeloperoxidase (MPO).
- Receiver operating characteristic (ROC) curves evaluated diagnostic accuracy.
Main Results:
- Pleural fluid MPO showed the highest accuracy in differentiating infectious and non-infectious PE (Area Under Curve = 0.86).
- MPO levels >550 µg/l identified infectious PE with 77.4% sensitivity and 90.4% specificity.
- Excluding purulent parapneumonic effusions, sensitivity remained 72.6%.
Conclusions:
- Pleural fluid MPO is a superior biochemical marker for distinguishing infectious from non-infectious pleural effusions.
- MPO offers valuable diagnostic information for PE classification.