Background Novel coronavirus (SARS-CoV-2) infects human lung tissue cells through angiotensin-converting enzyme-2 (ACE2), and the body sodium is an important factor for regulating the expression of ACE2. Through a systematic review, meta-analysis and retrospective cohort study, we found that the low blood sodium population may significantly increase the risk and severity of SARS-CoV-2 infection. Methods We extracted the data of serum sodium concentrations of patients with COVID-19 on admission from the articles published between Jan 1 and April 28, 2020, and analyzed the relationship between the serum sodium concentrations and the illness severity of patients. Then we used a cohort of 244 patients with COVID-19 for a retrospective analysis. Results We identified 36 studies, one of which comprised 2736 patients.The mean serum sodium concentration in patients with COVID-19 was 138.6 mmol/L, which was much lower than the median level in population (142.0). The mean serum sodium concentration in severe/critical patients (137.0) was significantly lower than those in mild and moderate patients (140.8 and 138.7, respectively). Such findings were confirmed in a retrospective cohort study, of which the mean serum sodium concentration in all patients was 137.5 mmol/L, and the significant differences were found between the mild (139.2) and moderate (137.2) patients, and the mild and severe/critical (136.6) patients. Interestingly, such changes were not obvious in the serum chlorine and potassium concentrations. Conclusions The low sodium state of patients with COVID-19 may not be the consequence of virus infection, but could be a physiological state possibly caused by living habits such as low salt diet and during aging process, which may result in ACE2 overexpression, and increase the risk and severity of COVID-19. These findings may provide a new idea for the prevention and treatment of COVID-19.

中文翻译：

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低血钠会增加COVID-19的风险和严重性：系统评价，荟萃分析和回顾性队列研究

背景技术新型冠状病毒（SARS-CoV-2）通过血管紧张素转换酶2（ACE2）感染人肺组织细胞，而机体钠是调节ACE2表达的重要因素。通过系统的回顾，荟萃分析和回顾性队列研究，我们发现低血钠人群可能会显着增加SARS-CoV-2感染的风险和严重性。方法我们从2020年1月1日至4月28日发表的文章中提取入院时COVID-19患者的血清钠浓度数据，并分析血清钠浓度与患者疾病严重程度之间的关系。然后，我们对244例COVID-19患者进行了回顾性分析。结果我们确定了36项研究，其中一项包括2736例患者。COVID-19患者的平均血清钠浓度为138.6 mmol / L，远低于人群中位水平（142.0）。重症/重症患者的平均血清钠浓度（137.0）显着低于轻度和中度患者（分别为140.8和138.7）。一项回顾性队列研究证实了这些发现，所有患者的平均血清钠浓度为137.5 mmol / L，轻度（139.2）和中度（137.2）患者以及轻度和重度患者之间存在显着差异/危急（136.6）患者。有趣的是，血清氯和钾的浓度变化不明显。结论COVID-19患者的低钠状态可能不是病毒感染的结果，但可能是由于生活习惯（例如低盐饮食和衰老过程）引起的生理状态，可能导致ACE2过表达，并增加了COVID-19的风险和严重性。这些发现可能为预防和治疗COVID-19提供了新的思路。