Lactate Dehydrogenase (LDH), a Risk Factor of Severe COVID-19 Patients

Among recent studies, the presence of any coexisting illness ―comorbidities―, was more common among patients with severe disease. Most of the patients had elevated levels of C-Reactive Protein (CRP), and lymphocytopenia was common, especially in severe cases, which was thought to be a result of reduction of CD3+, CD4+ and CD8+ T cells.

A new study showed that Lactate Dehydrogenase (LDH) could be identified as a powerful predictive factor for early recognition of lung injury and severe COVID-19 cases. And importantly, lymphocyte counts, especially CD3+, CD4+, and CD8+ T cells in the peripheral blood of COVID-19 patients, which was relevant with serum LDH, were also dynamically correlated with the severity of the disease.

Meanwhile, prolonged Prothrombin Time (PT) and elevated Lactate Dehydrogenase (LDH) was also found in more than 40% cases during the whole disease period, with elevated ALT and AST less common in COVID-19 patients.

LDH is a major player in glucose metabolism which is present in tissues throughout the body and catalyzes pyruvate to lactate. It is released from cells upon damage of their cytoplasmic membrane. Previous studies also had noted the importance of LDH as an indicator of lung diseases. In a study on Epstein-Barr Virus (EBV), researchers found that EBV infected B cells had more LDH transcripts than the uninfected B cells. In addition, the serum levels of LDH increased in Pneumocystis Pneumonia (PcP) patients, probably was due to lung injury. Among patients who were infected during the 2009 influenza A (H1N1) pandemic, 77.8% whose laboratory test showed LDH greater than 225 U/L had lung involvement, without difference between adult and children, which indicated that LDH elevation was associated with various pathogen including virus, and was relevant to lung injury. Furthermore, there was a case reported in 2017 that a patient with human Zika virus infection had markedly elevated LDH, which was associated with 70% mortality in further Zika infected animal study. They considered LDH as an indicator of multiorgan injury, not only affecting liver or cardiac function. LDH is found in all human cells, especially in myocardial and liver cells.

Finally, given the rapid spread of COVID-19, authors considered that an updated analysis of risk factors may help early recognition of the severity of the disease.

Link to the paper: https://doi.org/10.1101/2020.03.24.20040162

Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.

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