AUTHOR=Gille Thomas , Sesé Lucile , Aubourg Eric , Fabre Emmanuelle E. , Cymbalista Florence , Ratnam Kayaththiry Caroline , Valeyre Dominique , Nunes Hilario , Richalet Jean-Paul , Planès Carole 

TITLE=The Affinity of Hemoglobin for Oxygen Is Not Altered During COVID-19

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.578708

DOI=10.3389/fphys.2021.578708

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> A computational proteomic analysis suggested that SARS-CoV-2 might bind to hemoglobin (Hb). The authors hypothesized that this phenomenon could result in a decreased oxygen (O<sub>2</sub>) binding and lead to hemolytic anemia as well. The aim of this work was to investigate whether the affinity of Hb for O<sub>2</sub> was altered during COVID-19.</p><p><bold>Methods:</bold> In this retrospective, observational, single-center study, the blood gas analyses of 100 COVID-19 patients were compared to those of 100 non-COVID-19 patients. Fifty-five patients with carboxyhemoglobin (HbCO) ≥8% and 30 with sickle cell disease (SCD) were also included (“positive controls” with abnormal Hb affinity). P<sub>50</sub> was corrected for body temperature, pH, and PCO<sub>2</sub>.</p><p><bold>Results:</bold> Patients did not differ statistically for age or sex ratio in COVID-19 and non-COVID-19 groups. Median P<sub>50</sub> at baseline was 26 mmHg [25.2–26.8] vs. 25.9 mmHg [24–27.3], respectively (<italic>p</italic> = 0.42). As expected, P<sub>50</sub> was 22.5 mmHg [21.6–23.8] in the high HbCO group and 29.3 mmHg [27–31.5] in the SCD group (<italic>p</italic> &lt; 0.0001). Whatever the disease severity, samples from COVID-19 to non-COVID-19 groups were distributed on the standard O<sub>2</sub>-Hb dissociation curve. When considering the time-course of P<sub>50</sub> between days 1 and 18 in both groups, no significant difference was observed. Median Hb concentration at baseline was 14 g.dl<sup>–1</sup> [12.6–15.2] in the COVID-19 group vs. 13.2 g.dl<sup>–1</sup> [11.4–14.7] in the non-COVID-19 group (<italic>p</italic> = 0.006). Among the 24 COVID-19 patients displaying anemia, none of them exhibited obvious biological hemolysis.</p><p><bold>Conclusion:</bold> There was no biological argument to support the hypothesis that SARS-CoV-2 could alter O<sub>2</sub> binding to Hb.</p>