Methemoglobinemia is a hematologic disorder defined by pathologically elevated methemoglobin, an oxidized form of hemoglobin in which one or more heme iron atoms are in the ferric (Fe³⁺) rather than ferrous (Fe²⁺) state, impairing oxygen binding/release and producing tissue hypoxia. Normal methemoglobin levels are kept low by reductase enzyme systems (principally cytochrome b5 reductase), and the condition arises either congenitally, from a genetic deficiency of this enzyme, or is acquired through exposure to oxidizing substances that overwhelm the enzyme's reducing capacity. This topic belongs to hematology/clinical biochemistry, situated within the study of hemoglobin structure-function and oxygen transport physiology.
Methemoglobinemia is a hematologic disorder defined by pathologically elevated methemoglobin, an oxidized form of hemoglobin in which one or more heme iron atoms are in the ferric (Fe³⁺) rather than …