Background: The novel coronavirus disease (COVID-19) is caused by Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) which utilizes angiotensin converting enzyme2 (ACE2) to invade the host cells. This membrane-bound peptidase is widely distributed in the body; its activity antagonizes the renin-angiotensin-aldosterone system (RAAS). Once SARS-Cov2 enters the cell, it causes downregulation of ACE2, resulting in the unopposed activation of RAAS. The unregulated activity of the RAAS system can deteriorate the prognosis in COVID-19 patients. A soluble form of ACE2 (sACE2) was reported to have a role in the SARS-Cov2 invasion of the susceptible cells.

Aim of the study: This study aims to investigate the potential association of serum levels of sACE2 and RAAS components in severe COVID-19 patients compared to healthy individuals.

Methods: Eighty-five participants enrolled in the study were grouped into 45 non-hypertensive severe COVID-19 patients and 40 healthy individuals with comparable age and gender. Serum levels of sACE2, renin, angiotensin 2, and aldosterone by ELISA, and serum potassium level was measured by turbidimetric method.

Results: The results showed a significant difference in the serum levels of sACE2 (lower), renin, angiotensin 2, and aldosterone (higher) in COVID-19 patients compared to the control subjects (p-value <0.001; for all.

Conclusion: Non-hypertensive severe COVID-19 patients have lower sACE2 and higher RAAS peptide levels, and they can serve as diagnostic markers of severe COVID-19 patients.

Recommendations: we recommend a future study with a larger sample size that enrolls COVID-19 patients with different severity levels.

Keywords: Aldosterone, Angiotensin, COVID-19, Renin, Soluble angiotensin converting enzyme 2