methemoglobinemia

      decrease in the oxygen-carrying capacity of the red blood cells (erythrocytes (erythrocyte)) due to the presence of methemoglobin in the blood. The severity of the symptoms of methemoglobinemia is related to the quantity of methemoglobin present in the circulation and range from a bluish discoloration of the skin and mucous membrane to weakness, difficulty in breathing, and dizziness in the more severe cases.

      The iron component of the hemoglobin of the red blood cells must be in the reduced (deoxidized) state to bind with oxygen; methemoglobin contains the oxidized form of iron and is useless for oxygen transport. Normally, various organic catalysts or enzymes are active in keeping the iron in the reduced form. Hereditary methemoglobinemia occurs when there is an inborn defect in this enzyme system or when the hemoglobin molecule is abnormally structured (hemoglobin M) and is thereby more susceptible to oxidation of the iron component. Acquired methemoglobinemia may arise as a result of contact with certain drugs and chemicals that produce oxidant compounds in the circulation, causing the oxidation of iron to occur faster than the enzyme system can keep it in the reduced state.

      Treatment of hereditary methemoglobinemia usually includes the administration of reduction compounds such as methylene blue. Acquired methemoglobinemia usually disappears spontaneously when the cause is removed.

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Universalium. 2010.

Look at other dictionaries:

  • Methemoglobinemia — Classification and external resources ICD 10 D74 ICD 9 289.7 …   Wikipedia

  • methemoglobinemia — methemoglobinemia. См. метгемоглобинемия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Methemoglobinemia — The presence in the blood of methemoglobin, a form of hemoglobin that is useless for carrying oxygen and delivering it to tissues throughout the human body. Since hemoglobin is the key carrier of oxygen in the blood, its replacement by… …   Medical dictionary

  • methemoglobinemia — methemoglobinemija statusas T sritis ekologija ir aplinkotyra apibrėžtis Kūdikių liga, atsirandanti dėl methemoglobino, galinčio susidaryti vartojant nitratų turintį vandenį, pertekliaus kraujyje. atitikmenys: angl. methaemoglobinaemia;… …   Ekologijos terminų aiškinamasis žodynas

  • methemoglobinemia — noun Etymology: New Latin Date: 1888 the presence of methemoglobin in the blood …   New Collegiate Dictionary

  • methemoglobinemia — noun A form of toxic anemia characterized by the presence of methemoglobin in the blood …   Wiktionary

  • methemoglobinemia — met·hemoglobinemia …   English syllables

  • methemoglobinemia — |met+ noun ( s) Etymology: New Latin, from International Scientific Vocabulary methemoglobin + New Latin emia : the presence of methemoglobin in the blood due to conversion of part of the hemoglobin to this inactive form …   Useful english dictionary

  • acquired methemoglobinemia — methemoglobinemia caused by exposure to a toxic chemical or drug; many different agents have been implicated, including nitrate and nitrite compounds, sulfonamides, and aniline dyes. Called also toxic m …   Medical dictionary

  • congenital methemoglobinemia — hereditary methemoglobinemia any of several rare types caused by inherited conditions. Deficiency of cytochrome b5 reductase is an autosomal recessive condition that may be either confined to the erythrocytes and relatively symptom free or… …   Medical dictionary

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