Evaluation of Hematological Changes in COVID-19 Patients and Their Prognostic Value in Clinical Management

Abstract

COVID-19, caused by SARS-CoV-2, induces profound and dynamic hematological alterations that serve as reliable biomarkers for disease severity, progression, and prognosis. Key changes include lymphopenia (particularly severe ALC <0.5 × 10⁹/L), neutrophilia, thrombocytopenia, normocytic normochromic anemia, and elevated Red Cell Distribution Width (RDW). Integrated inflammatory indices such as the Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), and Systemic Immune-Inflammation Index (SII) have demonstrated strong predictive power for severe disease, ICU admission, mechanical ventilation, and mortality. Biochemical markers including hyperferritinemia (>255 µg/L), elevated LDH (>319 U/L), CRP (>117 mg/L), IL-6, and D-dimer further enhance risk stratification. These abnormalities reflect underlying mechanisms such as cytokine storm, direct viral effects on hematopoietic stem cells, immune dysregulation, NETosis, and consumptive coagulopathy. In clinical practice, these hematological parameters guide timely triage, anticoagulation intensity (per ASH 2025 guidelines), and immunomodulatory therapy decisions. Longitudinal monitoring also aids in identifying persistent changes associated with Long COVID. Overall, routine hematological assessment provides accessible, cost-effective, and actionable prognostic insights that significantly improve risk stratification and clinical management of COVID-19 patients.