From the Guidelines
Yes, a virus can cause elevated C-reactive protein (CRP) levels, as evidenced by the COVID-19 infection, which triggers a cytokine release syndrome (CRS) or "cytokine storm" that leads to increased pro-inflammatory cytokines and subsequently elevated CRP levels 1. When a viral infection such as COVID-19 occurs, the body's immune system responds by triggering inflammation, which leads to the liver producing more CRP as part of the acute phase response.
- The main pathogenesis of COVID-19 involves the attachment of the virus to angiotensin converting enzyme 2 (ACE2) receptors in the nasopharynx and respiratory epithelium, followed by the initiation of host immune responses and the formation of pro-inflammatory cytokines induced by the virus 1.
- The degree of increase in pro-inflammatory cytokines determines the degree of COVID-19-induced lung injury, and the more increase in pro-inflammatory cytokines, the higher the injury to lung tissue and the more severe the acute respiratory distress syndrome (ARDS), which could be related to higher mortality 1.
- The degree of increase in pro-inflammatory cytokines in COVID-19 is higher than that induced by other viruses, especially in older age and comorbid conditions, which may be due to pre-existing subclinical or subtle inflammations, represented by increased high-sensitive CRP (hsCRP) in these groups 1.
- The exaggerated increase in pro-inflammatory cytokines in COVID-19 could be due to hyperactivation of various kinds of immune cells in response to the N-protein of the virus, which is called "cytokine storm" and can cause acute lung injury, ARDS, and eventually multiorgan failure 1.
From the Research
Viral Infections and Elevated C-Reactive Protein (CRP)
- Viral infections can cause elevated CRP levels, as seen in severe COVID-19 cases, where CRP is highly predictive of the need for mechanical ventilation and may guide escalation of treatment 2.
- However, CRP values are not useful in defining the type of infection, as no significant differences were found between viral and atypical bacterial infections 3.
- Elevated CRP levels have been reported in various viral infections, including COVID-19, Dengue virus, Cytomegalovirus, Epstein Barr virus, Parvovirus B19, Herpes simplex 1 and 2 virus, and Influenza A and B 3.
Clinical Significance of CRP in Viral Infections
- CRP is an acute-phase protein that increases in response to inflammatory stimuli, and its levels can provide important information for guiding clinical diagnosis and treatment 2, 3.
- The assessment of host inflammatory status and identification of viral infection can be aided by acute-phase proteins, including CRP and procalcitonin 2.
- However, the use of CRP as a parameter to determine the difference between viral and atypical bacterial infections is limited, as it is not specific to the type of infection 3.
Treatment of Viral Infections and CRP Levels
- The treatment of viral infections, such as COVID-19, may involve the use of antiviral drugs, such as remdesivir, favipiravir, and lopinavir/ritonavir, which may have an impact on CRP levels 4, 5, 6.
- However, the effectiveness of these treatments in reducing CRP levels and improving clinical outcomes is still being studied, and more research is needed to fully understand their benefits and risks 5, 6.