Erythrocyte morphology as a clinical disease indicator in hospitalized COVID-19 patients

Most COVID-19 cases are mild, but some require hospitalization due to pneumonia, with symptoms like hypoxia and dyspnea. This has led to speculation about erythrocyte involvement in the infection. This study aimed to examine the differences in the presence of dysmorphic erythrocytes in COVID-19 patients upon admission compared to healthy subjects, as well as to assess these differences in relation to the severity of the clinical presentation of COVID-19.

This study included 150 participants: 100 COVID-19 patients and 50 healthy subjects who formed the control group. The COVID-19 positive participants were divided into two groups based on the deterioration or improvement of their health conditions during hospitalization. Hematological parameters were analyzed, and peripheral blood smears were prepared to observe morphological changes in erythrocytes.

The morphological changes observed in hospitalized COVID-19 patients included spiculated red blood cells (RBCs), spherocytes, stomatocytes, schistocytes, knizocytes, keratocytes, as well as mushroom- and cup-shaped RBCs. At admission, spiculated RBCs and spherocytes were more prevalent in patients showing improvement. Conversely, stomatocytes, knizocytes, keratocytes, and mushroom-shaped RBCs were more frequent in patients experiencing deterioration. Additionally, spiculated RBCs were more common in patients with improvement, while stomatocytes, schistocytes, knizocytes, keratocytes, mushroom-, and cup-shaped RBCs were more prevalent in deteriorating patients.

The complete blood count and the examination of peripheral blood smears in hospitalized patients may serve as fundamental tools to assist clinicians in differentiating disease severity and improving treatment decision-making.