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. Data are available upon reasonable request.

中文翻译：

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心包液的正常成分是什么？

目的 生化和细胞学心包液 (PF) 分析基本上是基于胸水成分的知识。本研究的目的是根据最先进的方法标准确定 PF 的参考区间 (RI)。方法 我们前瞻性地收集并分析了 2017 年 7 月至 2018 年 10 月期间接受择期心脏直视手术的连续受试者的 PF 和静脉血。研究入选的排除标准是术前检查或术中评估时的心包疾病证据，或任何其他条件可能会影响 PF 分析。结果 最终研究样本包括 120 名患者（中位年龄 69 岁，83 名男性，69.1%）。主要发现是 (1) 高水平的蛋白质、白蛋白和乳酸脱氢酶 (LDH)，但不是葡萄糖和胆固醇 (2) 高细胞性，主要以间皮细胞为代表。心包生化的 RI 为：蛋白质含量 1.7–4.6 g/dL PF/血清蛋白质比率 0.29–0.83，白蛋白 1.19–3.06 g/dL，心包至血清白蛋白梯度 0.18–2.37 g/dL，LDH 131–26 /L，PF/血清 LDH 比率 0.40–2.99，葡萄糖 80–134 mg/dL，总胆固醇 12–69 mg/dL，PF/血清胆固醇比率 0.07–0.51。光学显微镜下心包细胞的 RI 为：278–5608 × 106 有核细胞/L、40–3790 × 106 间皮细胞/L、35–2210 × 106 白细胞/L、19–1634 × 106 淋巴细胞/L。结论 PF 富含有核细胞、蛋白质、白蛋白、LDH，其含量与其他生物体液中的炎性渗出物一致。医生应停止根据未针对此设置验证的工具将 PF 解释为渗出液或漏出液。