Methemoglobinemia, also known as "met-H", is a usually genetic blood disorder characterized by the presence of a higher than normal level of methemoglobin in the blood.

Types

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Congenital methaemoglobinaemia ()

Due to an enzyme deficiency, the blood of met-H victims has reduced oxygen-carrying capacity. Instead of being red in colour, the arterial blood of met-H victims is brown. This results in the skin of Caucasian sufferers gaining a bluish cast. Hereditary met-H is caused by a recessive gene. If only one parent has this gene offspring will have normal-hued skin, but if both parents carry the gene there is a chance the offspring will have blue-hued skin.

Types include:

Acquired/Toxic methaemoglobinaemia ()

Acquired methemoglobinemia can be caused by the use of nitrite-containing drugs, such as amyl nitrite. Nitrates do not directly cause methemoglobinemia, however nitrate is readily metabolized to nitrite in infants and, in this case, can cause methemoglobinemia indirectly. Infants under six months of age are particularly susceptible to this effect. The current EPA standard of 10 ppm nitrate-nitrogen for drinking water is specifically designed to protect infants.

Treatment

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Methemoglobinemia is treated with the use of methylene blue, which restores the hemoglobin to its normal oxygen-carrying state.

Symptoms

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Symptoms of methemoglobinemia include headache, weakness, dizziness, and can progress to seizures, arrythmia, coma and death.

One visual indicator is a blue tint to the skin. The Fugate family in rural Appalachia is a common example. The small community and lack of transportation caused inbreeding, which led to the gene being spread among the family.Adams, Cecil. "The Straight Dope: Is there really a race of blue people?." The Straight Dope. 24 July 1998. 4 Jun 2006 .

References

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External Links

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• The Blue People of Kentucky
• Methemoglobinemia: Feeling Blue?

Methämoglobinämie