Methemoglobinemia

By:    Published: March 1, 2012

a a a

A handful of people in the world have a peculiar condition where their skin has a blue tint to it. Though it may seem like something out of an urban legend, this condition – called methemoglobinemia – is a real blood disorder that exists today. Methemoglobinemia has a unique set of symptoms and can be acquired or inherited.

Definition

To understand methemoglobinemia, it’s important to know a little bit about hemoglobin. Hemoglobin is the molecule found in red blood cells that is responsible for distributing oxygen to the body. Methemoglobinemia is a rare blood disorder in which an atypical form of hemoglobin, called methemoglobin, is produced in abnormal amounts.

While most people have less than one percent of methemoglobin in their blood, people with methemoglobinemia may have up to 20 percent of this form of hemoglobin. Methemoglobin is unable to release oxygen effectively, so methemoglobinemia causes body tissues to lack sufficient oxygen. This is a serious condition since, without oxygen, the muscles, brain and heart can cease to function.

The bluish skin tone associated with methemoglobinemia stems from the lack of oxygenation in the blood. According to ABC News Health, a person with methemoglobinemia will have blood that has a sort of chocolate color due to this lack of oxygen.

A famous case of methemoglobinemia occurred in the Fugate family, who lived in an isolated part of Appalachia in the 1800s. Due to their lack of contact with other towns and communities, many members of the Fugate family married cousins or other nearby families. One of the first Fugates in the area carried the recessive gene for methemoglobinemia, a trait which was passed down to many of his descendants. However, the condition is not just hereditary; there are also cases of methemoglobinemia which are acquired.

Types

Methemoglobinemia is either inherited or acquired.

  • Acquired methemoglobinemia is the more common form of this condition. It develops in some people after they have been exposed to certain foods, chemicals or drugs.
  • Inherited methemoglobinemia is rarer and more complex that acquired methemoglobinemia. It comes in two forms. The first occurs when both parents carry the recessive gene (even though they usually don’t have the condition themselves) and their child experiences a problem with an enzyme called cytochrome b5 reductase. This variety of inherited methemoglobinemia is one of two types. Type 1 methemoglobinemia occurs when red blood cells lack the enzyme, and type 2 methemoglobinemia occurs when the enzyme doesn’t function anywhere in the body. The second type of inherited methemoglobinemia occurs when there is a defect in the actual hemoglobin molecule. This is called hemoglobin M disease and it can occur when only one parent has the recessive gene.

Symptoms

The symptoms of methemoglobinemia vary depending on the form of the condition that a person has. The most common form – acquired methemoglobinemia – is associated with the following symptoms:

  • Bluish color in the skin
  • Fatigue
  • Lack of energy
  • Shortness of breath
  • Headaches

Meanwhile, type 1 methemoglobinemia and hemoglobin M disease are both associated only with the symptom of having bluish skin.

Type 2 methemoglobinemia is the most severe form of methemoglobinemia. The symptoms of this condition include developmental delays, mental retardation, seizures and an overall failure to thrive.

Causes And Risk Factors

Methemoglobinemia has two possible causes: inheriting a recessive gene from one or both parents or being exposed to certain drugs, foods or chemicals.

The risk for inherited methemoglobinemia is increased by having one or both parents who carry the recessive gene or having a family history of methemoglobinemia.

The risk for acquired methemoglobinemia increases with exposure to the chemicals, drugs and foods which have been identified as possible triggers for the disorder. Those triggers include benzene, antibiotics like dapsone or chloroquine, nitrities (which are sometimes use to keep meat from spoiling) or anesthetics like benzocaine and xylocaine.

Prevention

There is no sure way to prevent inherited methemoglobinemia except for not having biological children if you carry the recessive gene. Genetic counseling is recommended for those who have a family history of methemoglobinemia and are considering having children.

Acquired methemoglobinemia can be prevented by avoiding possible triggers of this form of the disorder. However, it’s important to note that every person exposed to these triggers will necessarily develop acquired methemoglobinemia.

Treatment

The treatment for methemoglobinemia varies depending on which form of the disorder an individual displays.

People with acquired methemoglobinemia usually find that their symptoms fade or disappear completely once they have identified the cause of the condition and are able to avoid exposure to it. In severe cases, a blood transfusion may be used as treatment.

Type 1 methemoglobinemia and hemoglobin M disease typically don’t require any treatment. Generally, people with these forms of the condition do not suffer any serious health complications related to their methemoglobinemia.

People with type 2 methemoglobinemia experience the most severe health problems and need treatment as soon as possible. Methylene blue is a medicine used to treat severe cases of methemoglobinemia, though it should not be utilized if the patient has a blood disease called G6PD deficiency. Ascorbic acid may also be used to reduce the level of methemoglobin, and alternative treatments like hyperbaric oxygen therapy and exchange transfusions are sometimes applied. Sadly, people with type 2 methemoglobinemia usually die within the first few years of life.

Sources:

More in Diseases & Conditions
New on SymptomFind
a a a  
RELATED ARTICLES
NEED ANSWERS?