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Exposure to exogenous oxidizing drugs and their metabolites (such as benzocaine, dapsone, and nitrates) may lead to an increase of up to a thousandfold of the methemoglobin formation rate, overwhelming the protective enzyme systems and acutely increasing methemoglobin levels. [citation needed]
Methemoglobin (British: methaemoglobin, shortened MetHb) (pronounced "met-hemoglobin") is a hemoglobin in the form of metalloprotein, in which the iron in the heme group is in the Fe 3+ state, not the Fe 2+ of normal hemoglobin.
Hemoglobin M disease is a rare form of hemoglobinopathy, characterized by the presence of hemoglobin M (HbM) and elevated methemoglobin (metHb) level in blood. [1] HbM is an altered form of hemoglobin (Hb) due to point mutation occurring in globin-encoding genes, mostly involving tyrosine substitution for proximal (F8) or distal (E7) histidine residues. [2]
Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. As a medication, it is mainly used to treat methemoglobinemia.It has previously been used for treating cyanide poisoning and urinary tract infections, but this use is no longer recommended.
Hemoglobin variants can be discovered through examination, routine laboratory testing, or evaluation of patients with severe anemia. [3] In some countries, all newborns are tested for hemoglobinopathies, thalassemias, and HbS.
Methemoglobin is also formed in small quantities when the dissociation of oxyhemoglobin results in the formation of methemoglobin and superoxide, O 2 −, instead of the usual products. Superoxide is a free radical and causes biochemical damage, but is neutralised by the action of the enzyme superoxide dismutase.
Methemoglobin is an oxidized form of hemoglobin attached to a ferric-state iron (Fe3+), which can therefore not carry and deliver oxygen to tissues. [15] The formation of methemoglobin occurs when electrons are not returned to the iron of a normal state hemoglobin, which is not preferred for a functioning organism.
Hemoglobinemia (or haemoglobinaemia) is a medical condition in which there is an excess of hemoglobin in the blood plasma.This is an effect of intravascular hemolysis, in which hemoglobin separates from red blood cells, a form of anemia.