Biomarkers in routine diagnosis of pleural effusions

Abstract

Background: Pleural fluid biochemical analysis is the first step in pleural effusion (PE) diagnostics. Our purpose was to analyse the utility of the biomarkers used at our clinic in the routine diagnosis of PE.Methods: We retrospectively reviewed the PE levels of proteins, lactate dehydrogenase (LDH), alpha amylase (AA), pH and glucose in 433 patients who were treated at the University Clinic Golnik in a one-year period and compared these values with the final identified aetiology of the effusions.Results: The majority of the effusions were determined to be a consequence of malignancy (n = 154) or infection (n = 108). In 94 cases the aetiology of the effusions was heart failure and in 54 cases other diseases, while 23 effusions remained aetiologically undetermined. Considering Light’s criteria, the vast majority of the effusions were correctly classified as exudates or transudates (97.1 %). Comparing paramalignant and malignant effusions, we detected significantly lower values of pleural fluid LDH (p < 0.0005) and proteins (p < 0.0005), and higher pH (p < 0.0005) values in the paramalignant effusions.Conclusion: We have found that pleural LDH and proteins are the most helpful biochemical parameters in our routine diagnosis of pleural effusions and helped us to correctly narrow the aetiological spectrum. Furthermore, significantly higher pleural LDH and protein values and a pH below 7.32 additionally facilitated distinguishing between malignant and paramalignant effusions. Parameters such as glucose and AA are useful in selected cases and have a limited role in routine diagnostics.