title: Routine measurement of pleural fluid amylase is not indicated.
abstract: BACKGROUND
  The routine measurement of pleural fluid amylase is frequently recommended, but the cost-effectiveness of this procedure is unknown.
  
  
  METHODS
  To assess the utility of routine measurement of pleural fluid amylase in evaluating pleural effusions, we measured amylase, glucose, lactate dehydrogenase, and protein levels and blood cell counts in 379 patients undergoing thoracentesis during a 22-month period from 1997 to 1999. Of these, 199 had effusions after cardiac surgery; 61, malignant; 48, transudative; 28, parapneumonic; 2, chylous; 2, rheumatoid; 1, tuberculous; and 1, from chronic pleuritis. There were 37 exudates of unknown origin.
  
  
  RESULTS
  Measurement of pleural fluid amylase levels did not assist in determining the origin of the effusion in any of the patients. Amylase levels greater than 100 U/L (normal serum level in our laboratory is 30-110 U/L) were found in 5 (1.3%) of 379 patients: 1 patient with congestive heart failure (amylase, 173 U/L), 2 with post-cardiac surgery effusions (144 U/L and 130 U/L), 1 with pneumonia (109 U/L), and 1 with lung cancer (105 U/L).
  
  
  CONCLUSIONS
  The routine measurement of pleural fluid amylase levels is neither clinically indicated nor cost-effective. We suggest that pleural fluid serum amylase levels be measured only if there is a pretest suspicion of acute pancreatitis, chronic pancreatic disease, or esophageal rupture.
authors.affiliation: Department of Medicine, Vanderbilt University , Nashville, Tenn, USA.
authors.forename: P
authors.initials: P
authors.lastname: Branca
authors.forename: R M
authors.initials: RM
authors.lastname: Rodriguez
authors.forename: J T
authors.initials: JT
authors.lastname: Rogers
authors.forename: D S
authors.initials: DS
authors.lastname: Ayo
authors.forename: J P
authors.initials: JP
authors.lastname: Moyers
authors.forename: R W
authors.initials: RW
authors.lastname: Light
mesh_terms: D000681:Amylases / Q000032:analysis*; D004796:Clinical Enzyme Tests / Q000191:economics; D001026:Coronary Artery Bypass; D003362:Cost-Benefit Analysis; D003365:Costs and Cost Analysis; D003937:Diagnosis, Differential; D004935:Esophageal Diseases / Q000150:complications / Q000175:diagnosis; D006801:Humans; D010195:Pancreatitis / Q000150:complications / Q000175:diagnosis; D010996:Pleural Effusion / Q000175:diagnosis / Q000191:economics / Q000201:enzymology* / Q000209:etiology*; D016066:Pleural Effusion, Malignant / Q000175:diagnosis; D012422:Rupture, Spontaneous
chemical_list: D000681:Amylases