Diagnostic value of ferritin analysis in pleural effusions

Ferritin was analysed with an immunoradiometric assay using anti-spleen ferritin antibodies, in pleural effusions (Pl) from 28 patients with malignant effusions (18 carcinoma, 10 mesothelioma), 15 patients with non-malignant exudative effusions of unknown aetiology, and from 12 patients with transudative effusions due to congestive cardiac failure. Geometric mean Pl-ferritin was 617 micrograms/l in carcinoma, 1301 micrograms/l in mesothelioma (p less than 0.01 against carcinoma), 931 micrograms/l in non-malignant exudates, and 178 micrograms/l in transudates (p less than 0.0001 against malignant and non-malignant exudates). There was no correlation between Pl-ferritin and Pl-protein, Pl-albumin or Pl-cell count. P1-ferritin displayed a wide overlap between the various groups, and was of no value in the discrimination between malignant and non-malignant exudates. In the differentiation between exudates and transudates, the diagnostic accuracy of Pl-ferritin was only slightly lower compared to Pl-protein and Pl-albumin. With the present method, analysis of Pl-ferritin appears to be of limited value in the routine diagnostic evaluation of pleural effusions.