Association of C4 and CH50 levels with cough and rhinorrhea in COVID-19 patients: A retrospective analysis in the Iranian population

Introduction

The wide spectrum of COVID-19 symptoms, ranging from mild manifestations to severe pulmonary damage and mortality, prompted this study to investigate the relationship between clinical symptoms and complement system (CS) activation in COVID-19 patients.

Materials and method

This retrospective study focused on 100 PCR-positive COVID-19 individuals admitted to Imam Khomeini and Bu Ali hospitals in Sari City from April to June 2021. The levels of C3 and C4 proteins in their blood were measured using nephelometry, and CH50 tests were done with single radial immunodiffusion to determine the activity of CS.

Results

The study found that high blood pressure, smoking, and diabetes were the most common underlying conditions among the patients, with prevalence rates of 29%, 24%, and 23%, respectively. Positive correlations were found between C4 and CH50 levels and the presence of cough and rhinorrhea in the subjects. Stratifying patients into 2 groups based on cough or rhinorrhea revealed a significant difference in CH50.

Conclusion

The findings suggest that COVID-19 patients with hypertension or diabetes mellitus may benefit from targeting CS for disease management.