Methods of diagnosis and/or prognosis of malignant disease from pleural effusion samples are disclosed. The methods typically include determining the normalized intensity of one or more biomarkers, such as acetone and 3-hydroxybutyate, in pleural effusion samples using nuclear magnetic resonance (NMR), such as proton NMR (1H-NMR) spectroscopy. Reference values for malignant disease diagnosis using the disclosed biomarkers are provided. Reference values for prognosis of median survival time based on the disclosed biomarkers are also provided.
