Outside of red blood cells, “good” ferrous iron – the only oxygen-carrying form – is oxidized uncontrollably to form the “bad” ferric and “ugly” ferryl forms of hemoglobin. When released into a person’s circulatory system, hemoglobin in these higher oxidation states eventually self-destructs, damaging molecules in surrounding tissue.
血红蛋白包含了亚铁血红素，一种含有铁元素的化合物。铁是一种过渡金属，可以氧化（或曰“生锈）。在红细胞之外，“好”的亚铁——唯一的携氧形式——被不可控地氧化，形成“坏”的三价铁和“丑”的高价铁的血红蛋白形式。当血红蛋白被释放到人的循环系统中时，高价铁形式最终会自我毁灭，伤害周围组织的分子。