Plasma ACE and ACE2 Levels Are Altered in Patients with COVID-19

Increasing disease severity was associated with higher mortality, elevated body mass index, and higher viral load estimates. Severe and critical illness was characterized by leukocytosis with neutrophilia, marked lymphopenia, anemia, elevated inflammatory and coagulation markers, renal dysfunction, and hypoalbuminemia. Plasma ACE2 levels declined progressively with increasing severity and were significantly lower in patients with mild-pneumonia, severe, or critical illness compared with asymptomatic or mild cases, showing a strong inverse correlation with severity. In contrast, plasma ACE levels increased significantly with disease severity. The resulting increase in the ACE/ACE2 ratio indicates a progressive shift toward the pro-inflammatory arm of the RAS, providing mechanistic insight into the COVID-19 pathophysiology.