The following pleural fluid protein associations have been noted:
1. If pleural fluid protein levels are 6-8 g/dL the malignancy conditions of multiple myeloma and Waldenstrom’s macroglobulinemia should be considered.
2. Pleural effusions with protein levels of 4 g/dL are characteristic of tuberculosis
3. Pneumocystis infections typically have a pleural fluid/serum protein ratio of < 0.5