We examined the serum concentration of endothelial dysfunction marker (angiopoietin-1), marker of NETosis (neutrophil elastase 2), kidney injury molecule-1 (KIM-1), which is also the receptor for SARS-CoV-2, and the level of the membrane-attacking complex (MAC) in hospitalized COVID-19 patients, to clarify the leading mechanisms of kidney damage. Here, ANGPT1 is linked to endothelial dysfunction.