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What is the normal composition of pericardial fluid?
  1. Sabrina Buoro1,
  2. Enrico Tombetti2,
  3. Ferruccio Ceriotti3,
  4. Caterina Simon4,
  5. Diego Cugola4,
  6. Michela Seghezzi1,
  7. Francesco Innocente4,
  8. Silvia Maestroni4,
  9. Maria del Carmen Baigorria Vaca1,
  10. Valentina Moioli1,
  11. Giulia Previtali1,
  12. Barbara Manenti1,
  13. Yehuda Adler5,
  14. Massimo Imazio6,
  15. Antonio Brucato2
  1. 1 Clinical Chemistry Laboratory, ASST Papa Giovanni XXIII, Bergamo, Italy
  2. 2 Department of Biomedical and Clinical Sciences, University of Milano and ASST Fatebenefratelli-Sacco, Milano, Italy
  3. 3 Clinical Laboratory, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, Milano, Italy
  4. 4 Internal Medicine and Cardiac Surgery, ASST Papa Giovanni XXIII, Bergamo, Italy
  5. 5 Dean for Medical Professions, College of Law and Business, Ramat Gan, Israel, Sackler Faculty of Medicine, Tel Aviv University, Mayanei Hayeshua, Medical Center, Bnei Brak, Israel
  6. 6 University Cardiology, Cardiovascular and Thoracic Department, AOU Città della Salute e della Scienza, Torino, Italy
  1. Correspondence to Professor Massimo Imazio, University Cardiology, Cardiovascular and Thoracic Department, AOU Città della Salute e della Scienza di Torino, Torino 10126, Piemonte, Italy; massimo_imazio{at}


Objective Biochemical and cytological pericardial fluid (PF) analysis is essentially based on the knowledge of pleural fluid composition. The aim of the present study is to identify reference intervals (RIs) for PF according to state-of-art methodological standards.

Methods We prospectively collected and analysed the PF and venous blood of consecutive subjects undergoing elective open-heart surgery from July 2017 to October 2018. Exclusion criteria for study enrolment were evidence of pericardial diseases at preoperatory workup or at intraoperatory assessment, or any other condition that could affect PF analysis.

Results The final study sample included 120 patients (median age 69 years, 83 men, 69.1%). The main findings were (1) High levels of proteins, albumin and lactate dehydrogenase (LDH), but not of glucose and cholesterol (2) High cellularity, mainly represented by mesothelial cells. RIs for pericardial biochemistry were: protein content 1.7–4.6 g/dL PF/serum protein ratio 0.29–0.83, albumin 1.19–3.06 g/dL, pericardium-to-serum albumin gradient 0.18–2.37 g/dL, LDH 141–2613 U/L, PF/serum LDH ratio 0.40–2.99, glucose 80–134 mg/dL, total cholesterol 12–69 mg/dL, PF/serum cholesterol ratio 0.07–0.51. RIs for pericardial cells by optic microscopy were: 278–5608 × 106 nucleated cells/L, 40–3790 × 106 mesothelial cells/L, 35–2210 × 106 leucocytes/L, 19–1634 × 106 lymphocytes/L.

Conclusions PF is rich in nucleated cells, protein, albumin, LDH, at levels consistent with inflammatory exudates in other biological fluids. Physicians should stop to interpret PF as exudate or transudate according to tools not validated for this setting.

  • pericardial effusion

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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  • SB, ET and FC contributed equally.

  • Contributors Study design, enrolment and data collection: SB, FC, CS, DC, MS, FI, SM, MdCBV, VM, GP, BM. Data management and statistical analysis: SB, AB, FC, ET. Manuscript draft, analysis of data and supervision: YA, MI, AB, SB, FC, ET. Manuscript revision and approval: all authors.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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