UCSF

Context

SARS-CoV-2 infects cells via the angiotensin converting enzyme 2 (ACE2) receptor, whose downstream effects "counterbalance" the classical renin angiotensin aldosterone system (RAAS).

Objective

We aimed to determine to what extent circulating RAAS biomarker levels differ in persons with and without COVID-19 throughout the disease course.

Methods

We measured classical (renin, aldosterone, aldosterone/renin ratio [ARR], Ang2, ACE activity) and nonclassical (ACE2, Ang1,7) RAAS biomarkers in hospitalized COVID-19 patients vs SARS-CoV-2 negative controls. We compared biomarker levels in cases with contemporaneous samples from control patients with upper respiratory symptoms and a negative SARS-CoV-2 PCR test. To assess RAAS biomarker changes during the course of COVID-19 hospitalization, we studied cases at 2 different times points ∼ 12 days apart. We employed age- and sex-adjusted generalized linear models and paired/unpaired t tests.

Results

Mean age was 51 years for both cases (31% women) and controls (50% women). ARR was higher in the first sample among hospitalized COVID-19 patients vs controls (P = 0.02). ACE activity was lower among cases at their first sample vs controls (P = <0.001). ACE2 activity, Ang 1,7, and Ang2 did not differ at the 2 COVID-19 case time points and they did not differ in COVID-19 cases vs controls. Additional adjustment for body mass index (BMI) did not change our findings.

Conclusions

High ARR, independent of BMI, may be a risk marker for COVID-19 hospitalization. Serum ACE activity was lower in patients with COVID-19 vs controls at the beginning of their hospitalization and then increased to similar levels as controls, possibly due to lung injury, which improved with inpatient disease management.