HPX and sickle cell disease: The effect of free heme on the hemostatic balance in vivo is a much more complex scientific question, influenced by variables such as the wide availability of heme scavengers such as hemopexin and albumin in plasma [52], the effects of heme on other discrete compartments of hemostasis [16], and an extremely complex network of cellular pathways that participate in the pathogenesis of hemolytic anemias such as sickle cell disease [53].