methemoglobin


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Related to methemoglobin: methemoglobin test, Methemoglobin reductase

methemoglobin

 [met-he´mo-glo″bin]
a hematogenous pigment formed from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state. A small amount is found in the blood normally, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function as an oxygen carrier.

met·he·mo·glo·bin (metHb),

(met-hē'mō-glō'bin),
A transformation product of oxyhemoglobin resulting from the oxidation of the normal Fe2+ to Fe3+, a process that converts heme to hematin; because methemoglobin contains water in firm union with ferric iron, it is chemically different from oxyhemoglobin; found in sanguineous effusions and in the circulating blood after poisoning with acetanilid or potassium chlorate, among other substances.
Synonym(s): ferrihemoglobin

methemoglobin

/met·he·mo·glo·bin/ (met-he´mo-glo″bin) a hematogenous pigment formed from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state. A small amount is found in the blood normally, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function as an oxygen carrier.

methemoglobin

(mĕt-hē′mə-glō′bĭn)
n.
A brownish-red form of hemoglobin that occurs when hemoglobin is oxidized either during decomposition of the blood or by the action of various oxidizing drugs or toxic agents. It contains iron in the ferric state and cannot function as an oxygen carrier.

methemoglobin

[met′hēməglō′bin, met·he′məglō′bin]
a form of hemoglobin in which the iron component has been oxidized from the ferrous to the ferric state. Methemoglobin cannot carry oxygen. It is a product of various oxidative reactions that constitute normal metabolic activity and is normally present in only trace amounts (about 1%) in the blood, but may increase in chronic inflammation. Maintenance of levels occurs by an active enzymatic reducing capability, the nicotinamide-adenine dinucleotide-methemoglobin reductase system present in normal red blood cells. Also spelled methaemoglobin. See also hemoglobin.

met·he·mo·glo·bin

(metHb) (met-hē'mŏglō'bin)
A transformation product of oxyhemoglobin because of the oxidation of the normal Fe2+ to Fe3+, thus converting ferroprotoporphyrin to ferriprotoporphyrin; useless for respiration; found in bloody effusions and in the circulating blood after poisoning with acetanilid, potassium chlorate, and other substances.
Synonym(s): hemiglobin, methaemoglobin.

Methemoglobin

A compound formed from hemoglobin by oxidation.
Mentioned in: Nephrotoxic Injury

methemoglobin

a compound formed from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state. A small amount of methemoglobin is normally present in the blood, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function as an oxygen carrier. See also hemoglobin.

methemoglobin reductase pathway
an intraerythrocyte enzyme system that maintains hemoglobin in a reduced state. A deficiency of the enzyme, resulting in the formation of methemoglobinemia with insufficient oxygenation of the blood, occurs in the dog.
References in periodicals archive ?
Methemoglobin becomes clinically relevant when the oxidative burden overwhelms the cellular capability for reduction.
Reduction of methemoglobin through flavin at the physiological concentration by NADPH-flavin reductase of human erythrocytes.
The coefficient of variation for methemoglobin saturation measurement was 0.
95% for nonsmokers, and mean methemoglobin levels were 0.
Blood levels taken at weekly intervals showed low, fluctuating levels of methemoglobin in all the heifers.
Two worrying aspects to the methemoglobin formation induced by topical benzocaine and injectable prilocaine are, first, the delay between the use of the drug and the appearance of sentinel cyanosis and, second, the propensity of benzocaine-induced methemoglobinemia to return many hours later.
The second potential complication is the buildup of excessive amounts of methemoglobin, which reduces the oxygen-carrying capacity of blood.
Perioperative monitoring may be problematic because of the interference of methemoglobin with pulse oximetry function.
The combination of a defibrillator with noninvasive carboxyhemoglobin (SpCO) and methemoglobin (SpMet) monitoring capabilities means that more cases of potentially life-threatening conditions may be detected and treated earlier to improve patient safety, outcomes and recoveries.
Toxic methemoglobinemia is a toxic disorder in which the methemoglobin concentration in the blood is elevated due to various substances found in drugs, pesticides, etc.
Masimo guarantees that when a hospital replaces its standard SpO2 adhesive sensors with Masimo rainbow[R] ReSposable SpHb Sensors and begins monitoring noninvasive hemoglobin (SpHb), pleth variability index (PVI[R]), and methemoglobin (SpMet[R]), in addition to Masimo SET SpO2, pulse rate, and perfusion index (PI), the incremental price paid for the rainbow sensors will be exceeded by a reduction in blood transfusion related costs.
The technique is based on Beer's Law and takes advantage of the unique but overlapping wavelength spectra of blood oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin.