Due to exposure to drugs and chemicals commonly used in cardiac and anaesthetic procedures, which oxidizes haemoglobin to form methaemoglobin
The addition of ascorbic acid to nitrateamendedtissues changesblood andbiochemical parameters as well.These results indicated that ascorbic acid can reduce methaemoglobin
 ormay augment the function of endogenous free radical scavengers and decreases the adverse effect of nitrates on body cells .
We have revealed characteristic changes in clinical laboratory parameters--increased lipid peroxidation, decreased AOA in the blood and superoxide dismutase activity, increased MDA and methaemoglobin
levels, mild inflammatory changes on the complete blood count with no clinical signs of disease exacerbation, reduced non-specific resistance, the imbalance of cellular and humoral immunity, suggesting a long-term antigenic stimulation, restructuring of the receptors of immunocompetent cells, the inhibition of the receptor CD56+ expression, which reduces the antiviral and anti-tumor immunity.
Several screening tests are available such as dye decolourization test, monospotflurorescent test, methaemoglobin
reduction test and formazan test.
These analysers are equipped with a cooximeter, which enables determination of bilirubin and various forms of haemoglobin (the total, oxy-, carboxy-, sulpho-, and methaemoglobin
The red cell nicotinamide adenine dinucleotide hydrogen (NADH) dependent methaemoglobin
reductase or diaphorase I enzyme (Breaking et al., 1951; Gibson and Harrison, 1947), protects the erythrocyte from an accumulation of methaemoglobin
After nitrite absorption through fish gills it reacts with the hemoglobin iron in the blood, converting it in methaemoglobin
which is not capable to transport oxygen.
When carbon monoxide combines with haemoglobin it forms carboxyhaemoglobin and methaemoglobin
which reduces the oxygen-carrying capacity of the blood and can result in hypoxic stress (Alp et al 2006).
People who suffer from methaemoglobinaemia have high blood methaemoglobin
concentration with usual symptoms like cyanosis, headache, dizziness, shortness of breath, and loss of consciousness.
Arterial blood gas analysis showed oxygen saturation of 98%, pH 7.36, [P.sub.a]C[O.sub.2] 26 mmHg, [P.sub.a][O.sub.2] 123 mmHg, bicarbonate 14 mmol/l, lactate 8.5 mmol/l and methaemoglobin
Relation of nitrate contamination of groundwater with methaemoglobin
level among infants in Gaza.
Carboxyhaemoglobin and methaemoglobin
findings in burnt bodies.