Serum ACE as a prognostic biomarker in COVID-19: a case series.

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. High s-ACE could indicate lower ACE2 activity and therefore more widespread and severe SARS-CoV2 infection, owing to virally mediated downregulation of ACE2 (1). Dysregulation of the Renin-Angiotensin-Aldosterone system (RAAS) are found in comorbidities known as risk factors for increased morbidity and mortality, such as hypertension and cardiovascular disease (2).