Diagnostic value of lactoferrin analysis in pleural effusions

Lactoferrin was analysed with an ELISA in pleural effusions from 21 patients with malignant exudative effusions (15 carcinomas and 6 mesotheliomas), 12 patients with non-malignant exudative effusions of unknown aetiology, 11 patients with transudative effusions due to congestive heart failure, 12 patients with exudative effusions secondary to infection, and 2 patients with tuberculous effusions. Median pleural fluid lactoferrin was 133 micrograms/l (range 25-435) in carcinomas, 55 micrograms/l (23-185) in mesotheliomas, 198 micrograms/l (31-530) in non-malignant exudates, 68 micrograms/l (17-205) in transudates, 1815 micrograms/l (1380-2050) in infectious exudates and 107 micrograms/l (88-125) in tuberculosis. Due to a wide overlap between the various groups pleural fluid lactoferrin appears to be of limited value in the routine diagnostic evaluation of non-infectious pleural effusions, but seems to separate infectious exudates from non-infectious exudates.