REN and COVID-19: Renin, a protease produced by renal juxtaglomerular cells in its active form, cleaves angiotensinogen, released mainly by the liver, to form Ang I. A pathophysiological mechanism underlying the cardio-metabolic conditions associated with a greater risk of morbidity and mortality in COVID-19 is the imbalance between ACE and its homologous ACE2, with a decreased activity of the latter and impairment of its protective effects.