Methemoglobinemia
Author : Dr Pierre Hébert
Translation by Dr. Khyali R. Mittal
Methemoglobinemia
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Author : Dr Pierre Hébert |
Description: combination of the oxygen with ferrous iron (Fe+2) of the hemoglobin molecule results in the formation of oxyhemoglobin with the iron in the ferric form (Fe+3) which could no more accept other oxygen molecule. Methemoglobin is the hemoglobin in which the iron is in the ferric form when any oxygen molecule combined with it. In the normal process of the reaction of oxygen with the hemoglobin, there is formation of a small quantity of methemoglobin which is normally reduced by intrinsic mechanisms of the erythrocyte. The methemoglobin will be produced in pathological way when the intrinsic mechanisms of the red blood cell are oversaturated. The most frequently encountered conditions which produce methemoglobin are intoxication due to acetaminophen in the cat, intoxication due to nitrites in cattle and intoxication due to red maple leaf in the horse. The blood having a large quantity of methemoglobin is of very dark colour typically described as "chocolate brown". In this case, the test tube on the left hand side from a cat with acetaminophen intoxication compared with a normal blood sample on the right hand side. |
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