• Methemoglobin (British: methaemoglobin) (pronounced "met-hemoglobin") is a hemoglobin in the form of metalloprotein, in which the iron in the heme group is in the Fe3+ (ferric) state, not the Fe2+ (ferrous) of normal hemoglobin. (wikipedia.org)
  • The NADH-dependent enzyme methemoglobin reductase (a type of diaphorase) is responsible for converting methemoglobin back to hemoglobin. (wikipedia.org)
  • The word methemoglobin derives from the Ancient Greek prefix μετα- (meta-: behind, later, subsequent) and the word hemoglobin. (wikipedia.org)
  • It works by converting hemoglobin to methemoglobin, which allows for the binding of cyanide (CN-) anions by ferric (Fe3+) cations and the formation of cyanomethemoglobin. (wikipedia.org)
  • Percentage of methemoglobin is calculated by dividing the concentration of methemoglobin by the concentration of total hemoglobin. (wikipedia.org)
  • Upon exiting the body, bloodstains transit from bright red to dark brown, which is attributed to oxidation of oxy-hemoglobin (HbO2) to methemoglobin (met-Hb) and hemichrome (HC). (wikipedia.org)
  • The NADH-dependent enzyme methemoglobin reductase (diaphorase I) converts methemoglobin back to hemoglobin (yaay! (medicowesome.com)
  • Due to this enzyme, only one to two percent of your hemoglobin is methemoglobin. (medicowesome.com)
  • So you basically oxidize hemoglobin and its derivatives to methemoglobin in the presence of alkaline potassium ferricyanide. (medicowesome.com)
  • Cercacor, makers of Ember® - the world's first non-invasive hemoglobin tracker for endurance athletes, today announced that users can now also measure and monitor the dyshemoglobins carboxyhemoglobin and methemoglobin. (cercacor.com)
  • Methemoglobin is a chemically altered type of hemoglobin that also does not carry oxygen. (cercacor.com)
  • Methemoglobin is an oxidized form of hemoglobin in which iron exists in the ferric (Fe 3+ ) state as opposed to ferrous (Fe 2+ ). (medscape.com)
  • The pathway responsible for reducing most methemoglobin (95%-99%) back to hemoglobin is the NADH-dependant methemoglobin reductase system, in which the enzyme cytochrome-b5 reductase5plays a crucial role in a transfer of electrons from NADH to methemoglobin. (medscape.com)
  • Methemoglobinemia is usually asymptomatic when methemoglobin levels are less than 15% of total hemoglobin. (medscape.com)
  • The provider looks at how the powder turns a substance in the blood called methemoglobin into normal hemoglobin . (medlineplus.gov)
  • Methemoglobin is a form of hemoglobin that does not carry oxygen. (amperordirect.com)
  • Hemoglobin electrophoresis is abnormal in HbM disease, but normal with NADH-methemoglobin reductase deficiency [McKenzie 2010]. (cdc.gov)
  • ATSDR Case Studies: Nitrate/Nitrite Toxicity] In some cases, methemoglobin-forming compounds cause denaturation of hemoglobin (Heinz bodies) followed by hemolytic anemia. (haz-map.com)
  • Excretion of methemoglobin, a transformation product of hemoglobin, into urine. (diagnose-me.com)
  • An assessment of methemoglobin levels is indicated as part of numerous tests used when methemoglobinemia is clinically suspected. (medscape.com)
  • High values of methemoglobin indicate methemoglobinemia, which can be hereditary or acquired. (medscape.com)
  • Acquired methemoglobinemia, which is far more common, results from overproduction of methemoglobin due to drug, toxin, and chemical substance exposures. (medscape.com)
  • Related tests/panels: The methemoglobin level is tested as part of a series of tests in the evaluation of methemoglobinemia. (medscape.com)
  • [ 3 ] As discussed in Interpretation, methemoglobinemia results from either an overproduction of methemoglobin that exceeds these protective pathways or a defect in the pathways themselves. (medscape.com)
  • You may have a rare form of methemoglobinemia if this test does not significantly lower the blood level of methemoglobin. (medlineplus.gov)
  • 1-2% Normal Less than 10% metHb - No symptoms 10-20% metHb - Skin discoloration only (most notably on mucous membranes) 20-30% metHb - Anxiety, headache, dyspnea on exertion 30-50% metHb - Fatigue, confusion, dizziness, tachypnea, palpitations 50-70% metHb - Coma, seizures, arrhythmias, acidosis Greater than 70% metHb - High risk of death This may be further compounded by the "functional hemoglobin's" decreased ability to release oxygen in the presence of methemoglobin. (wikipedia.org)
  • Liposome-encapsulated methemoglobin (metHb@Lipo) has been developed as a novel antidote for cyanide poisoning. (elsevierpure.com)
  • Here, we investigated the pharmaceutical stability of the metHb@Lipo suspension after one-year storage as a ready-to-use formulation at 4 °C, room temperature (23-28 °C) and 37 °C. The liposomal integrity of metHb@Lipo was observed after one year of storage at all storage temperatures with no physicochemical change or methemoglobin leakage outside the liposome. (elsevierpure.com)
  • The chocolate-brown appearance of methemoglobin (MetHb) does not change with time. (cdc.gov)
  • Methemoglobin reacts with potassium cyanide to form cyanmethemoglobin , which has maximum absorption at 540 nm. (medicowesome.com)
  • Methemoglobin comes to the rescue in cyanide poisoning! (medicowesome.com)
  • Methemoglobin has high affinity for cyanide radical and forms cyanomethemoglobin. (medicowesome.com)
  • This study tested whether exogenous stroma-free methemoglobin (SFmetHb) can prevent depression of hemodynamics and metabolism during canine cyanide poisoning. (asahq.org)
  • Two techniques, the cyanide derivative method and the multiple wavelength method, were used to determine methaemoglobin concentrations in blood samples from 25 species of marine teleosts and elasmobranchs captured on the Australian Great Barrier Reef. (edu.au)
  • For hereditary methemoglobinemias, reduced enzyme activity is seen with NADH-methemoglobin reductase deficiency, but normal in HbM disease. (cdc.gov)
  • This study investigated the effect of cashew seed fume on lactate dehydrogenase (LDH) activity, methemoglobin (Hi), carboxyhemoglobin (HbCO) and sulfhemoglobin (SHb) in the blood of rats exposed to cashew seed fumes (CSF), via the dynamic exposure system. (oalib.com)
  • The Measurement of Carboxyhemoglobin and Methemoglobin using a Non-Invasive Pulse CO-Oximeter. (masimo.ca)
  • Non-Invasive Measurements of Carboxyhemoglobin and Methemoglobin in Children with Sickle Cell Disease. (masimo.ca)
  • Measurement of Carboxyhemoglobin and Methemoglobin by Pulse Oximetry: A Human Volunteer Study. (masimo.ca)
  • By knowing their carboxyhemoglobin and methemoglobin levels, athletes may be able to change their environment, diet, and exercise intensity to impact and improve their measurements - and thus their general well being. (cercacor.com)
  • Bringing the ability to measure carboxyhemoglobin and methemoglobin to the athlete is a big deal," explained Johnathan Edwards, M.D. - an anesthesiologist, former team doctor to several pro cycling teams, and also an avid cyclist. (cercacor.com)
  • Making carboxyhemoglobin and methemoglobin data available to athletes is part of Cercacor's commitment to make Ember an extremely valuable and integral element of elite athletes' training regimen," stated Cercacor's Founder & CEO Joe Kiani. (cercacor.com)
  • Methemoglobin is expressed as a concentration or a percentage. (wikipedia.org)
  • Percentage of methemoglobin is likely a better indicator of illness severity than overall concentration, as underlying medical conditions play an important role. (wikipedia.org)
  • The current status of continuous noninvasive measurement of total, carboxy, and methemoglobin concentration. (masimo.ca)
  • A methemoglobin concentration beyond 70% is usually fatal. (medscape.com)
  • Adverse effects, blood pressure, heart rate, haemoglobin concentra-tion, per cent methaemoglobin in blood and plasma nitrite and nitrate concentration were recorded frequently for 24 h after each administration of sodium nitrite. (inchem.org)
  • To examine the relationship between circulating methemoglobin and nitrite/nitrate concentrations and to compare these markers of nitric oxide overproduction with clinical variables in children diagnosed with septic shock. (nih.gov)
  • Circulating methemoglobin and nitrite/nitrate concentrations were significantly higher in children diagnosed with septic shock in comparison with healthy control children (p = .01 and .05, respectively). (nih.gov)
  • Circulating methemoglobin and nitrite/nitrate concentrations are increased in children diagnosed with septic shock. (nih.gov)
  • Circulating methemoglobin measurements are not superior to plasma nitrite/nitrate concentrations as an indicator of endogenous overproduction of nitric oxide in children diagnosed with septic shock. (nih.gov)
  • Concentrations of methaemoglobin (the oxidized non-functional ferric form of haemoglobin) in the blood of marine fish are poorly documented. (edu.au)
  • The low methaemoglobin concentrations in fish studied on the Great Barrier Reef indicate high water quality and healthy physiological condition. (edu.au)
  • Patients diagnosed with septic shock had blood specimens taken on study entry and every 6 hrs for 72 hrs for methemoglobin and nitrite/nitrate determinations. (nih.gov)
  • There were no significant relationships between methemoglobin and nitrite/nitrate or between methemoglobin and any other clinical variable. (nih.gov)
  • EPR spectroscopy of nitrite complexes of methemoglobin. (duke.edu)
  • Abu Naser AA, Ghbn N, Khoudary R. Relation of nitrate contamination of groundwater with methaemoglobin level among infants in Gaza. (who.int)
  • Intense exercise causing oxidative stress can cause a rise in methemoglobin. (cercacor.com)
  • Recent studies have shown an increase of methemoglobins (due to oxidative stress) in athletes one hour after cycling or running at 75% of their peak oxygen intake. (cercacor.com)
  • Owing to oxidative stresses, methemoglobin is always being produced within red blood cells, but its levels are kept low by enzymic pathways that work to reduce the molecule. (medscape.com)
  • Methemoglobin and nitric oxide therapy in Ugandan children hospitalized for febrile illness: results from a prospective cohort study and randomized double-blind placebo-controlled trial. (masimo.ca)
  • A higher level of methemoglobin will tend to cause a pulse oximeter to read closer to 85% regardless of the true level of oxygen saturation. (wikipedia.org)
  • A high level of methaemoglobin would cause a pulse oximeter to have a reading of around 85% regardless of the actual oxygen saturation level. (amperordirect.com)
  • Denzer, M. L. & Mowery, C. & Comstock, H. A. & Maheswarappa, N. B. & Mafi, G. & VanOverebeke, D. L. & Ramanathan, R., (2020) "Characterization of the Cofactors Involved in Non-enzymatic Metmyoglobin/Methemoglobin Reduction In Vitro", Meat and Muscle Biology 4(1). (iastatedigitalpress.com)
  • Although methaemoglobin generally accounted for less than 2% of total haemoglobin, systematic errors occurred when these two standard methods, developed for mammalian blood, were applied to the blood of some fish species. (edu.au)
  • In human blood a trace amount of methemoglobin is normally produced spontaneously, but when present in excess the blood becomes abnormally dark bluish brown. (wikipedia.org)
  • Increased levels of methemoglobin are found in blood stains. (wikipedia.org)
  • Normally, methylene blue quickly lowers the level of methemoglobin in the blood. (medlineplus.gov)
  • Methemoglobin results in distinct changes in blood color and oxygen carrying capacity. (cdc.gov)
  • Consequently, the multiple wavelength method generally was more reliable for estimating methaemoglobin in the blood of marine fish. (edu.au)
  • timing of this measurement was uncertain, Blood gas samples in the hospital caring for the 45-year-old patient were analyzed with a Ciba-Corning 2500 co-oximeter, which the hospital reported was sensitive for methemoglobin. (cdc.gov)
  • Methemoglobin Levels in Generally Anesthetized Pediatric Dental Patients Receiving Prilocaine versus Lidocaine. (masimo.ca)
  • Also drugs and pesticides can increase methemoglobin, such as (using) Lidocaine, and Dapsone. (cercacor.com)
  • Twelve patients with intracranial hematomas who had undergone diffusion imaging were retrospectively identified during a 2-year period (four intracellular oxyhemoglobin, seven intracellular deoxyhemoglobin, one intracellular methemoglobin). (ajnr.org)
  • It has been suggested that restricted diffusion is present within hematomas with intact red cell membranes (intracellular oxyhemoglobin, deoxyhemoglobin, and methemoglobin) (4) . (ajnr.org)
  • 0.05) differences in the % methemoglobin level of rats in all groups. (oalib.com)
  • The main source of drinking water for and methaemoglobin level were assessed the families of each study infant was as using the chi-squared test. (who.int)
  • The higher percentage of methaemoglobin can be genetic or caused by exposure to certain chemicals and medications. (amperordirect.com)
  • Alternative pathways by which methemoglobin can be reduced, which become more important in deficiencies of the primary pathway, involve the NADPH-methemoglobin reductase system, reducing agents such as ascorbic acid, and reduced glutathione. (medscape.com)
  • This may result in the formation of methaemoglobin. (inchem.org)
  • Food containing nitrates such as processed and cured meats can increase methemoglobin. (cercacor.com)
  • Improved Accuracy of Methemoglobin Detection by Pulse CO-Oximetry during Hypoxia. (masimo.ca)
  • Methaemoglobin: The test compound (CAS 13863 -31 -5) has been found to be devoid of Methaemoglobin-inducing capacity after single oral administration of 5000 mg/kg in young adult rats. (europa.eu)