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methaemoglobin (metHb)

Name methaemoglobin (metHb)
Specimen requirements 1 ml of EDTA blood
Collection instructions We recommend filling an extra tube when sampling.
Procedure remarks False low values if left sitting > 5 h, after haemolysis, half-life period approx. 45 h;
leukocytosis, hyperlipoproteinaemia and bilirubinaemia are disruptive, with false high values
Substances/medications that can cause methaemoglobinaemia: sodium nitrite, nitroglycerin, amyl nitrates, sulfonamides, pyridines, primaquine, benzocaine, lidocaine, procaine
Note: infant methaemoglobinaemia after water containing nitrate
Clinical utility suspicions of hereditary methaemoglobinaemia, toxic haemolytic anaemia
Methodology photometry
Reference ranges 0.2-1.4 %,
Symptoms:
Asymptomatic: < 15 %,
Headache, dizziness, cyanosis: 15-20 %,
Nausea, cyanosis: 20-45 %,
Severe cyanosis, attacks, confusion: 45-70 %,
Lethal: > 70 %
Remarks Testing currently takes place in a contract laboratory