BACKGROUND: Coronavirus disease 2019 (COVID-19) is often associated with thrombosis. Elevated levels of soluble C-type lectin-like receptor 2 (sCLEC-2), a biomarker for platelet activation, have been reported in COVID-19. Therefore, we examined the behavior of sCLEC-2 levels and their relationship with thrombosis.

METHODS: The clinical course of inflammatory and thrombotic biomarkers was assessed in 271 patients with COVID-19.

RESULTS: Inflammatory biomarkers such as C-reactive protein, procalcitonin and presepsin levels were significantly increased in patients with COVID-19, and these behaviors differed among the clinical course or stages. The plasma D-dimer levels increased slightly and gradually. Platelet counts were within the normal range, and plasma sCLEC-2 levels were markedly increased in most patients with COVID-19. There were 17 patients with thrombosis in this study. Although there was no significant difference in various biomarkers between COVID-19 patients with and without thrombosis, the super formula of sCLEC-2xD-dimer/platelet count in patients with thrombosis was significantly higher than in those without thrombosis. Furthermore, this super formula was significantly higher in COVID-19 patients with severe or critical illness than in those with mild or moderate illness.

CONCLUSION: Elevation of the super formula of sCLEC-2xD-dimer/platelet count was associated with the thrombosis in patients with COVID-19 suggesting the thrombosis in COVID-19 may be caused by the development of microthrombosis.