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Related to methemoglobin: methemoglobin test, Methemoglobin reductase


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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

met·he·mo·glo·bin (metHb),

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
Farlex Partner Medical Dictionary © Farlex 2012


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.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


(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.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A compound formed from hemoglobin by oxidation.
Mentioned in: Nephrotoxic Injury
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Methemoglobin was found to be 1.2% in the patient, who was normal a day after surgery, and the patient was discharged after 3 days without any problem (11).
Deoxygenated/oxygenated hemoglobin, under the influence of specific chemical agents, is changed into derivatives: methemoglobin, S-nitrosohemoglobin, carbonous oxide hemoglobin, sulphhemoglobin, cyanomethemoglobin [3].
Concerning methemoglobin, results have indicated a significant increase of its percentage in females exposed to Pb and Pb-DD alike and that compared to the control.
Methemoglobin increased significantly over time in the iNO treated groups compared to the placebo treated, thus, serving as a marker of exposure to iNO [20](Figure 4).
We used a set of clinical and laboratory examination methods: clinical laboratory testing (complete blood count--leukocytes, eosinophils, lymphocytes), biochemical testing (AST AOA, MDA, lipid hydroperoxide, nitric oxide, superoxide dismutase, methemoglobin) immune testing (indicators of non-specific immunity--phagocytic activity, cellular immunity--CD3+, CD4+, CD8+, CD19+, CD56+, and humoral immunity--total IgE, IgA, IgG).
Symptoms are typically noticed at methemoglobin concentrations of greater than 15%.
Methemoglobin level was measured to be 16.2% at the time of hospitalization.
When the pulmonary capillaries are adequately oxygenated the NO combines with saturated hemoglobin to form methemoglobin and nitrite and these are the predominant byproducts that enter the systemic circulation.
I would like to add to this well written article that we have also reported acquired methemoglobinemia cases with administration of cytanest in puerperal women with G6PD deficiency and infants in whom erythrocyte cytochrome 65 reductase was assoyed (1-4), which is the main enzyme for methemoglobin reductase in erythrocytes as mentioned by the authors.
His methemoglobin concentration was 66.7% (normal: 1%-3%), his hemoglobin concentration was 14.3 g/dL (normal: 13.8-17.2 g/dL), and his platelet count was 338,000/[mm.sup.3] (normal: 150,000-400,000/[mm.sup.3]).
An azide methemoglobin method for hemoglobin determination in blood.