Methemoglobin, Blood

Laboratory assay overview

The iron in Hemoglobin is normally maintained in the ferrous state by several effective mechanisms so that only a small percentage of the total hemoglobin is in the form of Methemoglobin. The production of Methemoglobin by oxidation of the iron to the ferric state, renders the hemoglobin incapable of interacting reversibly with molecular oxygen. The oxygen affinity of the unaffected heme is also increased, resulting in the decreased release of oxygen to the tissues at low partial pressure of oxygen. ⁠⁠⁠⁠⁠⁠⁠ Methemoglobinemia is usually caused by exposure to various chemical agents, many which contain nitrogen. An increase in Methemoglobin can also occur due to Methemoglobin Reductase Deficiency (Congenital Methemoglobinemia).