metHb


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metHb

Abbreviation for methemoglobin.

methaemoglobin

A haemoglobin that results when oxyhaemoglobin in a ferrous (Fe2+) state is transformed into a ferric (Fe3+) state, which cannot transport O2. Low levels of methaemoglobin are always present in the circulation, but markedly increase after exposure to certain anaesthetics, benzocaines, nitrates, nitrites, phenacetin, etc., resulting in methaemoglobinaemia.
 
Ref range
• Normal, < 3% total MetHb.
• Cyanosis, 10–20% MetHb.
• Anoxia > 30% MetHb.

Specimen
Serum in sodium heparin (green top tube).
 
Method
Spectrophotometry.

metHb

Abbreviation for methemoglobin.

methaemoglobin

; MetHb transformation product of oxyhaemoglobin, where normal ferrous iron content (Fe2+) is oxidized to ferric iron (Fe3+); MetHb forms a very strong bond with oxygen, so that oxygen does not dissociate readily within tissues, with resultant compromise of cellular respiration and relative tissue ischaemia

MetHb

methemoglobin.

metHb

methemoglobin.
References in periodicals archive ?
Under physiological conditions, NADH-cytochrome b5 reductase is responsible for the removal of 95-99% of the MetHb (5).
On the other hand, the effectiveness and safety of inhalation of nebulized nitroglycerin (Neb-NTG) was tested in children with ventricular septal defect and pulmonary hypertension (VSD-PH) and MetHb level was below 1.
The formation of metHb involves the direct or indirect oxidation of hemoglobin to such an extent that the reductive pathways are overwhelmed, thereby resulting in high concentrations of metHb.
Increased temperature causes oxidation of hemoglobin to MetHb ([Fe.
1982) suggested that diarrhea produces an oxidant stress that increases MetHb production and that acidosis impairs the MetHb reductase systems.
2] and MetHb causes moderate underestimation in the higher S[O.
Arterial blood was noted to be dark brown, and CO-oximetry analysis showed a MetHb fraction of 23% (<2%), an F[O.
The effects of the addition of bilirubin, metHb, or oxyHb on the native bilirubin concentrations in these 10 AFs are shown in Table 1.
Two pools of red blood cells were formed, one with a nominal MetHb value of 0% and the other with a nominal value of 100% [prepared with potassium nitrite, as outlined previously (12, 13)].
To reduce metHb and to suppress autooxidation during oxygen-equilibrium studies, the metHb reducing system prepared according to the method of Hayashi et al.
2]Hb, COHb, and MetHb may be suitable for quality control in MCA of hemoglobin derivatives.
Because MetHb fractions >5% can lead to toxicity, monitoring of MetHb throughout therapy is required.