For example, angiotensin II and aldosterone could possibly better reflect the relative activities of ACE and ACE2 and have more merit as biomarkers of RAAS dysfunction in COVID-19 (2). Patients using ACE inhibitors or angiotensin II receptor blockers were excluded (N = 2), as these drugs can interfere with s-ACE levels (4), leaving 13 patient for further analysis. We have earlier proposed that serum ACE (s-ACE) could be used as a biomarker for severity in COVID-19 due to an assumed inverse relationship between ACE and ACE2. [Extracted from the article]