The Bottom Line: The pleural fluid amylase is elevated in patients with pleural effusions secondary to esophageal perforation, pancreatic disease, or malignant disease (Broaddus and Light, 2016).
References: Broaddus VC, and Light RW. Pleural Effusion. In Murray and Nadal’s Textbook of Respiratory Medicine (6th ed). 2016:79.
Villena V, Perez V, Pozo F, et al. Amylase levels in pleural effusions: a consecutive unselected series of 841 patients. Chest. 2002 Feb;121(2):470-474.
Summary: There’s an association between high amylase levels in pleural fluid and a neoplastic cause of the effusion. A very high amylase level strongly suggests a malignant etiology. Also, high levels of amylase in effusions secondary to pancreatitis are widely known. The mechanism seems to be associated with an increase in microvascular permeability. Exceedingly high levels have been reported in pancreatic pseudocysts (Villena et al, 2002). In approximately 10% of malignant effusions, the pleural fluid amylase level is mildly elevated. The site of the primary tumor in such patients is usually not the pancreas. Malignancy can be differentiated from pancreatic disease with amylase isoenzymes because the amylase with malignant effusions is primarily of the salivary type (Broaddus and Light, 2016)).