Lactate dehydrogenase and C-reactive protein as predictors of respiratory failure in CoVID-19 patients

Clin Chim Acta. 2020 Oct;509:135-138. doi: 10.1016/j.cca.2020.06.012. Epub 2020 Jun 9.


Objective: The dramatic worldwide CoVID-19 infection requires the identification of a reliable and inexpensive tool to quickly discriminate patients with a more unfavorable outcome.

Methods: We performed routine laboratory tests suitable to identify tissue damage and inflammatory status in 123 consecutive CoVID-19 patients admitted to the Emergency Department of the hospital of Piacenza (Emilia-Romagna, Northern Italy). The results were correlated with patients' respiratory function evaluated by the partial pressure of arterial oxygen to fraction of inspired oxygen ratio (PaO2/FiO2).

Results: The most common laboratory abnormalities were lymphocytopenia and elevated values of C-reactive protein (CRP) and lactate dehydrogenase (LDH). Aspartate aminotransferase (AST), alanine aminotransferase (ALT) and creatine kinase (CK) were also increased. The respiratory performance (PaO2/FiO2) showed a strong inverse correlation with LDH (r = 0.62, r2 0.38, p value < 0.0001) and CRP (r = 0.55, r2 0.31, p value < 0.0001). PaO2/FiO2 values also showed a significant inverse correlation with age (r = -0.37, p < 0.0001), AST (r = -0.31, p < 0.01), WBC (r = -0.49, p < 0.0001), neutrophils count (r = -0.5, p < 0.001). ROC curves showed a sensitivity of 75% and specificity of 70% for the LDH cut-off value of 450 U/L and a sensitivity of 72% and specificity of 71% for the CRP cut-off value of 11 mg/dl in identifying CoVID-19 with moderate-severe ARDS.

Conclusions: LDH and CRP may be related to respiratory function (PaO2/FiO2) and be a predictor of respiratory failure in CoVID-19 patients. LDH and CRP should be considered a useful test for the early identification of patients who require closer respiratory monitoring and more aggressive supportive therapies to avoid poor prognosis.

Keywords: Acute respiratory failure; CRP; CoVID-19; CoVID-19 pneumonia; Italian epidemic; LDH.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Betacoronavirus*
  • Biomarkers / blood
  • C-Reactive Protein / metabolism*
  • COVID-19
  • Clinical Laboratory Techniques / methods
  • Clinical Laboratory Techniques / trends
  • Coronavirus Infections / blood*
  • Coronavirus Infections / diagnosis
  • Coronavirus Infections / epidemiology
  • Female
  • Humans
  • Italy / epidemiology
  • L-Lactate Dehydrogenase / blood*
  • Male
  • Middle Aged
  • Pandemics
  • Patient Admission / trends
  • Pneumonia, Viral / blood*
  • Pneumonia, Viral / diagnosis
  • Pneumonia, Viral / epidemiology
  • Predictive Value of Tests
  • Respiratory Insufficiency / blood*
  • Respiratory Insufficiency / diagnosis
  • Respiratory Insufficiency / epidemiology
  • Retrospective Studies
  • SARS-CoV-2
  • Young Adult


  • Biomarkers
  • C-Reactive Protein
  • L-Lactate Dehydrogenase