Prognostic Significance of Lactate Dehydrogenase (LDH) in COVID-19 Morbidity and Mortality

COVID-19 pandemic remains a major global health problem due to its widespread prevalence and high rates of morbidity and mortality. Finding prognostic biochemical markers that can identify patients requiring immediate medical intervention is of critical importance in clinical practice. This single-center retrospective study aims to evaluate the prognostic significance of the tissue injury marker lactate dehydrogenase (LDH) in predicting the risk of death due to COVID-19. Our study included (78) COVID-19 patients admitted to the isolation ward of Tishreen University Hospital in Latakia, from 1 January to 31 July, 2021. The average age of the patients was 63.3 years, with 57.7% being male. The mean oxygen saturation on admission was 78%, and the mortality rate was 46.2%. A significant association between low oxygen saturation and increased mortality rates was observed, with LDH levels being markedly elevated in deceased patients compared to survivors. The results also suggested a role for thrombotic events and inflammatory response in the deterioration of cases, as significant increases in D-DIMER, C-reactive protein, and the neutrophil-to-lymphocyte ratio were noted among the deceased. Additionally, the study revealed a negative correlation between LDH levels and oxygen saturation, as well as a positive correlation with liver enzymes [Alanine Transaminase (ALT) and Aspartate Transaminase (AST)], creatinine, D-DIMER, and NLR. Using logistic regression analysis, LDH was found to be an independent marker for predicting mortality, with a cut-off value of 727 U/L yielding a sensitivity of 66.7% and specificity of 81%. These findings suggest that LDH may serve as an important prognostic indicator for identifying patients at higher risk of mortality.