Diagnostic Significance of Pleural Fluid Lactate Concentration in Pleural and Pulmonary Diseases

Abstract
Pleural fluid samples from 198 patients were analysed in order to evaluate the usefulness of lactate concentration as a diagnostic test for separating infectious from non-infectious processes in the pleural cavity. Pleural fluid lactate was quantified by means of a gas chromatographic method. The highest lactate levels were found in patients with septic pleuritis. Significantly lower values were observed in cases with malignancies. With a cut off value of 10 mmol/l, the predictive value of a positive test was 0.94 and of a negative test 1.0. Because of the high predictive values of the test, measurement of lactate concentration in pleural fluid offers a rapid and useful information in the differentiation between infectious and non-infectious pleural disease.