Abstract
Introduction: Pleural effusions caused by heart failure and hepatic hydrothorax are usually transudates. 20- 40% can be misclassified as exudates by Light's criteria. However, there are parameters that can help to identify false exudates in these patients.
Objective: To evaluate the usefulness of albumin and protein gradients, as well as albumin ratio to identify false exudates in patients with heart failure and hepatic hydrothorax.
Methods: We retrospectively reviewed all consecutive patients who underwent a diagnostic thoracentesis in our pleural unit. 361 pleural effusions were analysed. Statistical analysis was retrospective descriptive applied in univariate and multivariate.
Results: We identified 246 patients with the clinical diagnosis of heart failure (HF)-related and 115 with hepatic hydrothorax (HH)-related effusions. 87 of the 246 (35.4%) from heart failure, and 39 of the 115 (33.9%) from hepatic hydrothorax were misclassified as exudates by standard Light's criteria. The albumin and protein gradients and the pleural–to–serum albumin ratio were calculated in all of them. An albumin gradient higher than 1.2 g/dL were identified in 73 (70%) and 22 (56%) of the HF and HH false exudates, respectively. A serum–to–pleural fluid protein gradient >3.1 g/dL identified 64 cases (62%) and 18 (46%). Finally, a pleural fluid–to–serum albumin ratio <0.6 had 59 (57%) and 22 (56%), respectively.
Conclusion: The albumin gradient >1.2 g/dL as well as the protein gradient >3.1 g/dL are useful to identify transudate in misclassified hepatic hydrothorax. In false exudates from cardiac origin, albumin gradient >1.2 g/dL is the most suitable parameter.
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