title: The composition of normal pericardial fluid and its implications for diagnosing pericardial effusions.
abstract: BACKGROUND
  Pericardial fluid obtained at pericardiocentesis is often subjected to biochemical and hematological analysis, and interpreted using criteria borrowed from pleural effusions. However, the validity and diagnostic yield of this approach is uncertain. Moreover, there is little data regarding the normal composition of the physiological pericardial fluid, which could serve as a reference for pathological effusions.
  
  
  METHODS
  Pericardial fluid from 30 patients undergoing elective open heart surgery was collected. Patients were excluded if they had known pericardial disease, had systemic disorders known to be associated with pericardial disease, or if the fluid samples were hemolytic. The biochemical and hematological parameters of the fluid were determined using standard laboratory techniques, and compared with the results obtained for concurrently drawn venous blood.
  
  
  RESULTS
  The median age of the study population was 64.5 +/- 10.6 years. Chemistry results of soluble molecules were consistent with the plasma ultrafiltrate nature of the fluid. However, fluid lactate dehydrogenase (LDH) level was unexpectedly high, averaging 2.4 times the serum level, and the mean protein level was 0.6 of the serum level. No correlation was found between comorbidities of patients and fluid characteristics. Fluids contained an average of 1430 leukocytes/muL, with a differential count that was predominated by lymphocytes (53.2 +/- 14%) and monocytes (11.6 +/- 6%).
  
  
  CONCLUSIONS
  The composition of the physiologic pericardial fluid is remarkable for high LDH and protein content, and for predominance of lymphocytes. Thus, the biochemical criteria useful for diagnosing pleural effusions are probably not applicable for differentiating transudative from exudative pericardial effusions, and lymphocytosis should be interpreted cautiously.
authors.affiliation: Department of Medicine F, Sheba Medical Center, Sackler School of Medicine, Tel-Aviv University, Tel-Hashomer, Israel. sben-horin@013.net.il
authors.forename: Shomron
authors.initials: S
authors.lastname: Ben-Horin
authors.forename: Ami
authors.initials: A
authors.lastname: Shinfeld
authors.forename: Erez
authors.initials: E
authors.lastname: Kachel
authors.forename: Angela
authors.initials: A
authors.lastname: Chetrit
authors.forename: Avi
authors.initials: A
authors.lastname: Livneh
mesh_terms: D000368:Aged; D015897:Comorbidity; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D008875:Middle Aged; D010490:Pericardial Effusion / Q000737:chemistry* / Q000166:cytology / Q000453:epidemiology; D010493:Pericarditis / Q000175:diagnosis* / Q000453:epidemiology; D011446:Prospective Studies
chemical_list: D007770:L-Lactate Dehydrogenase