Biologically Active Substance
methemoglobin Audio
meth·e·mo·glo·bin [ met-hee-muh-gloh-bin, -hem-uh-, -hem-uh- ]
Subclass of:
Hemoglobin
Etymology:
Greek meta = change + haima = blood + Latin globulin = a small ball
Definitions related to methemoglobin:
  • 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.
    NCI Dictionary of Cancer Terms
    U.S. National Cancer Institute, 2021
  • A product of hemoglobin produced by oxidation of the iron atom from the ferrous to the ferric state.
    NCI
    U.S. National Cancer Institute, 2021
  • 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.
    CRISP Thesaurus
    National Institutes of Health, 2006
  • An assessment of methemoglobin levels is indicated as part of numerous tests used when methemoglobinemia is clinically suspected. The reference range of methemoglobin is 0%-1% of the total hemoglobin level (0.
    Medscape
    WebMD, 2025
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