Biochemical and Immune Indicators of COVID-19 Severity

Background: Coronaviruses (CoVs) are a class of RNA viruses that infect humans and variousanimals. They enter host cells via ACE2 receptors, which are widely distributed in organssuch as the heart, lungs, kidneys, and the digestive tract. COVID-19 infection causes systemicillness, characterized by fever, cough, fatigue, sputum production, dyspnea, appetite loss, andsometimes diarrhea. It can disrupt, damage, or even cause failure of multiple organs, particularly the lungs, kidneys, and sites of prior injury. Immune activation is marked by heightenedT-lymphocyte and macrophage responses, producing elevated levels of cytokines, notablyinterleukins such as IL-2, IL-4, and IL-6, which play complex and sometimes antagonistic rolesin immune regulation.Objective: To investigate alternative laboratory markers for the diagnosis and prognosis ofCOVID-19, particularly in settings where RT-PCR testing is unavailable, focusing on the role ofinflammatory markers and biochemical parameters.Methods: During periods when RT-PCR testing was inaccessible because of logistical constraints, conventional laboratory tests were utilized to establish diagnostic and prognostic criteria for COVID-19. These included measurement of serum ferritin, interleukin-6 (IL-6), lactatedehydrogenase (LDH), and hematological parameters such as hemoglobin levels to assess anemia and iron status.Results: Patients with COVID-19 frequently exhibited rapid elevation of ferritin levels, whichcorrelated with increased IL-6 concentrations. Hyperferritinemia was associated with anemiaand excessive iron loss. LDH levels were also elevated and served as an independent predictorof mortality, regardless of underlying conditions.Conclusion: In the absence of RT-PCR testing, routine laboratory markers—including ferritin,IL-6, LDH, and hematological profiles—can serve as valuable tools for the diagnosis and prognostic assessment of COVID-19. Elevated ferritin and LDH levels, in particular, are linked toincreased disease severity and higher mortality risk.