Association of serum lactate dehydrogenase and C-reactive protein with disease severity in hospitalised COVID-19 patients

Objective: Coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus, can lead to critical illness in hospitalised patients. Elevated levels of certain biomarkers are often associated with worse clinical outcomes. Two such biomarkers are lactate dehydrogenase (LDH), an enzyme found in nearly all body tissues that is released upon cell damage, and C-reactive protein (CRP), a protein produced by the liver in response to inflammation. This manuscript examines the relationship between LDH and CRP levels and their association with disease severity and clinical outcomes in critically ill patients with COVID-19. Methods: A cross-sectional study was conducted on 200 hospitalised COVID-19 patients and 20 age- and sex-matched healthy controls. SARS-CoV-2 infection was confirmed by RT-PCR targeting the ORF1ab, E, and N genes. Serum LDH and CRP levels were measured using a Cobas C111 clinical chemistry analyser. Results: COVID-19 patients had significantly higher median serum LDH and CRP levels [Provide values, e.g., LDH: 450 U/L (IQR: 350-580)] compared to healthy controls [LDH: 180 U/L (IQR: 150-210), p<0.001]. Both biomarkers showed a significant positive correlation with disease severity (p<0.001), with the highest levels observed in the severe patient group. Patients over 50 years old had significantly higher concentrations than younger patients. Conclusion: Elevated serum LDH and CRP levels are associated with increased disease severity in hospitalised COVID-19 patients, suggesting their potential utility as accessible prognostic biomarkers.