Methemoglobinemia (patient information)
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Methemoglobinemia |
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Methemoglobinemia On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Methemoglobinemia is a blood disorder in which an abnormal amount of methemoglobin -- a form of hemoglobin -- is produced. Hemoglobin is the protein in red blood cells that carries and distributes oxygen to the body.
With methemoglobinemia, the hemoglobin can carry oxygen but is unable to release it effectively to body tissues.
What are the symptoms of Methemoglobinemia?
Symptoms of type 1 methemoglobinemia (erythrocyte reductase deficiency) include:
- Bluish coloring of the skin
Symptoms of type 2 methemoglobinemia (generalized reductase deficiency) include:
- Developmental delay
- Failure to thrive
- Intellectual disability
- Seizures
Symptoms of hemoglobin M disease include:
- Bluish coloring of the skin
Symptoms of acquired methemoglobinemia include:
- Bluish coloring of the skin
- Headache
- Fatigue
- Shortness of breath
- Lack of energy
What causes Methemoglobinemia?
This condition can be passed down through families (inherited or congenital). Or, it is caused by exposure to certain drugs, chemicals, or foods (acquired).
There are two forms of inherited methemoglobinemia. The first form is passed on by both parents. The parents usually do not have the condition themselves, but they carry the gene that causes the condition. It occurs when there is a problem with an enzyme called cytochrome b5 reductase.
There are two types of this form of methemoglobinemia:
- Type 1 (also called erythrocyte reductase deficiency) occurs when red blood cells lack the enzyme.
- Type 2 (also called generalized reductase deficiency) occurs when the enzyme doesn't work anywhere in the body.
The second form of inherited methemoglobinemia is called hemoglobin M disease. It is caused by defects in the hemoglobin protein itself. Only one parent needs to pass on the abnormal gene for the child to inherit the disease.
Acquired methemoglobinemia is more common than the inherited forms. It occurs in some people after they are exposed to certain chemicals and drugs, including:
- Anesthetics such as benzocaine
- Benzene
- Certain antibiotics (including dapsone and chloroquine)
- Nitrites (used as additives to prevent meat from spoiling)
The condition may also occur in infants who are very ill or who are fed too many vegetables containing nitrates (such as beets).
When to seek urgent medical care?
Call your health care provider if you have a family history of methemoglobinemia and you develop symptoms of this disorder.
Call your health care provider or emergency services (911) immediately if you have severe shortness of breath.
Diagnosis
Methemoglobinemia can be diagnosed with a blood test.
A baby with this condition will have a bluish skin color (cyanosis) at birth or shortly afterward. Arterial blood gases and pulse oximetry tests may be done.
Treatment options
A medicine called methylene blue is used to treat severe methemoglobinemia. Methylene blue may be dangerous in patients who have or may be at risk for a blood disease called G6PD deficiency, and should not be used. If you or your child has G6PD deficiency, always tell your health care provider before receiving treatment.
Ascorbic acid may also be used to reduce the level of methemoglobin.
Alternative treatments include hyperbaric oxygen therapy and exchange transfusions.
In most cases of mild acquired methemoglobinemia, no treatment is needed. But you should avoid the medicine or chemical that caused the problem. Severe cases may need treatment, which may include a blood transfusion.
Where to find medical care for Methemoglobinemia?
Directions to Hospitals Treating Methemoglobinemia
What to expect (Outlook/Prognosis)?
People with type 1 methemoglobinemia and hemoglobin M disease usually do well. Type 2 methemoglobinemia is much more serious, and usually causes death within the first few years of life.
People with acquired methemoglobinemia usually do very well once the drug, food, or chemical that caused the problem is identified and avoided.
Possible complications
- Shock
- Seizures
- Death
Prevention
Genetic counseling is recommended for couples with a family history of methemoglobinemia who are considering having children.