Biomarkers for iron metabolism among patients hospitalized with community-acquired pneumonia caused by infection with SARS-CoV-2, bacteria, and influenza.

Abstract

Ferritin, the central iron storage protein, has attracted attention as a biomarker of severe COVID‐19. Few studies have investigated regulators of iron metabolism in the context of COVID‐19. The aim was to evaluate biomarkers for iron metabolism in the acute phase response to community‐acquired pneumonia (CAP) caused by SARS‐CoV‐2 compared with CAP caused by bacteria or influenza virus in hospitalized patients. A cross‐sectional study of 164 patients from the Surviving Pneumonia Cohort recruited between January 8, 2019 and May 26, 2020. Blood samples were collected at admission and analyzed for levels of C‐reactive protein (CRP), ferritin, soluble transferrin receptor, erythroferrone, and hepcidin. Median (IQR) hepcidin was higher in SARS‐CoV‐2 with 143.8 (100.7–180.7) ng/mL compared with bacterial and influenza infection with 78.8 (40.1–125.4) and 53.5 (25.2–125.8) ng/mL, respectively. The median ferritin level was more than 2‐fold higher in patients with SARS‐CoV‐2 compared with the other etiologies (p < 0.001). Patients with SARS‐CoV‐2 had lower levels of erythroferrone and CRP compared with those infected with bacteria. Higher levels of hepcidin and lower levels of erythroferrone despite lower CRP levels among patients with SARS‐CoV‐2 compared with those infected with bacteria indicate alterations in iron metabolism in patients with SARS‐CoV‐2 infection.