胸液可因多种疾病引起,在进行病因诊断过程中,首先应鉴别它是渗出液抑或漏出液,以进一步作有关检查。一般比重、蛋白含量与细胞学检查仍是传统的常规化验项目。通常当胸液比重>1.016(或1.018)、蛋白量>25g/L(2.5g/dl)或>30g/L(3.ug/dl)、细胞数>5× Pleural fluid can be caused due to a variety of diseases, in the process of etiological diagnosis, it should first identify whether it is exudate or leakage of fluid to further make the relevant checks. The general proportion, protein content and cytology remains the traditional routine laboratory project. Usually when the specific gravity of the pleural fluid is> 1.016 (or 1.018), the amount of protein is> 25g / L (2.5g / dl) or> 30g / L