Methemoglobinemia (metHb) is a rare condition that reduces the ability of red blood cells to carry oxygen. It is caused when a genetic mutation or environmental toxins turn hemoglobin (the iron-rich ...

Blood cancers, a category that includes polycythemia vera (PV), are a risk factor for severe COVID-19. As such, managing your risk and taking steps to prevent COVID-19 if you have PV are important.