umls-concept:C0025635 | skos:definition | CSP: compound formed from hemoglobin by oxidation of the ferrous to the ferric state with essentially ionic bonds; a small amount is normally present in the blood but injury or toxic agents can convert a larger proportion of hemoglobin to methemoglobin, which does not function reversibly as an oxygen carrier.,NCI: A product of hemoglobin produced by oxidation of the iron atom from the ferrous to the ferric state.,NCI: A form of hemoglobin found in the blood in small amounts. Unlike normal hemoglobin, methemoglobin cannot carry oxygen. Injury or certain drugs, chemicals, or foods may cause a higher-than-normal amount of methemoglobin to be made. This causes a condition called methemoglobinemia. | lld:umls |