Evaluating Serial LDH (Lactate dehydrogenase) Monitoring as a Marker for Severity and Early Lung Fibrosis in COVID-19 Pneumonia: Insights from a Study in an Indian Tertiary Care Center

Abstract

Background: COVID-19 pneumonia is a heterogeneous disease with variable effects on lung parenchyma, airways and vasculature, leading to long-term impacts on lung functions. Although Lung is the primary target organ involved in coronavirus disease-19 (COVID-19), many patients had pulmonary and extrapulmonary effects due to immune activation pathways and direct virus-induced lung damage. In COVID-19, pneumonia pathophysiology constitutes different pathways like immune activation, inflammatory, thrombogenic and immediate viral affection to lungs and extrapulmonary tissues.  Objective: Robust data on LDH is available as a prognostic marker in haematology, malignancy, and pneumocystis pneumonia, and we have analyzed its usefulness in COVID-19 pneumonia. Methodology: Prospective, observational and interventional study included 1000 COVID-19 cases confirmed with RT PCR. All patients were assessed with lung involvement documented and categorized on HRCT thorax, oxygen saturation, inflammatory marker as LDH at the entry point and follow-up. Age, gender, Comorbidity use BIPAP/NIV and outcome with or without lung fibrosis as per CT severity were vital observations. Statistical analysis is done by using the Chi-square test.  Results: CT severity score at the entry point with LDH level has a significant association (p<0.00001). LDH level is significantly associated with illness duration (p<0.00001). Comorbidities were significantly associated with normal and abnormal LDH levels, respectively (p<0.00001). LDH level has a significant association with oxygen saturation (p<0.00001). BIPAP/NIV requirement during treatment in critical care settings has a significant association with LDH level (p<0.00001). BIPAP/NIV requirement timing during hospitalization has a significant association with LDH level (p<0.00001). Follow-up LDH titer during hospitalization compared to entry point Normal and Abnormal LDH has a significant association in post-covid lung fibrosis, respectively (p<0.00001).   Conclusion: LDH is a readily available and universally acceptable inflammatory marker in the COVID-19 pandemic, and 'follow-up titers' have documented a crucial role in predicting the severity of illness and assessing response to treatment during hospitalization. 'Follow-up LDH titer' during hospitalization and discharge can be an early predictor of post-covid lung fibrosis. Keywords: COVID-19 Pneumonia; LDH; Oxygen Saturation; Inflammatory Marker; Post Covid Lung Fibrosis