A condition in which the iron in the hemoglobin molecule (the red blood pigment) is defective, making it unable to carry oxygen effectively to the tissues.
Causes, incidence, and risk factors
There are two forms of inheritable methemoglobinemia. Most hereditary cases result from a deficiency in the enzyme cytochrome b5 reductase (Type II). The other inheritable type, called hemoglobin M disease (Type I), is an autosomal dominant condition (which means you only need one affected parent to inherit it) characterized by an inability to convert methemoglobin back to hemoglobin. This usually causes few problems. Exposure to certain chemicals may also cause an increase in the production of methemoglobin. These chemicals include nitrites (used commonly to prevent spoilage of meat), xylocaine, and benzene.
Treatment
Medications used to treat this disorder include:
methylene blue or 1 to 2 grams of ascorbic acid daily (to treat type I or II b5R deficiency) cyanosis caused by hemoglobin M disease tends to be benign but does not respond to treatment cyanosis caused by exposure to an offending chemical is treated by avoiding that chemical, blood or exchange transfusion for a patient in shock, and repeated doses of IV methylene blue
Calling your health care provider
Call your health care provider if there is a family history of methemoglobinemia and you develop symptoms of this disorder. Call your health care provider or emergency services immediately if there is severe shortness of breath .
Prevention
Genetic counseling is recommended for prospective parents with a family history of methemoglobinemia.