How is methemoglobinemia inherited?

This condition is inherited in an autosomal recessive pattern , which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is hereditary methemoglobinemia?

Hereditary methemoglobinemia resulting from methemoglobin reductase deficiency (cytochrome-b5 reductase deficiency) is very rare. Mutations in the b5 reductase gene cause two distinct phenotypes.

Is methemoglobinemia dominant or recessive?

The inheritance pattern of the congenital enzyme deficiency form of the disease is autosomal recessive. Hb M is inherited in an autosomal dominant pattern. There is no association between sex and the frequency of congenital methemoglobinemia.

Can you be born with methemoglobinemia?

Methemoglobinemia is a condition that some babies are born with (congenital) or some develop early in life (acquired). Acquired methemoglobinemia is more common than the congenital form. It can be caused by exposure to a variety of substances and by some health conditions.

What are symptoms of methemoglobinemia?

What are the symptoms of methemoglobinemia?

• headache.
• shortness of breath.
• nausea.
• rapid heart rate.
• fatigue and lethargy.
• confusion or stupor.
• loss of consciousness.

How is inherited methemoglobinemia treated?

Treatment of methemoglobinemia revolves around administration of methylene blue and/or ascorbic acid. Although ascorbic acid alone is sufficient to alleviate the cyanosis in milder cases, the reaction rate is slower than that of the combined treatment.

When is methemoglobinemia treated?

The diagnosis is confirmed by the level of methemoglobin in blood (1, 6). The treatment with specific antidote is usually recommended in patients with blood methemoglobin level of >20% in symptomatic patients and >30% in asymptomatic patients.

How is methemoglobinemia treated?

Methylene blue is used to treat severe cases of MetHb, and doctors may prescribe ascorbic acid to reduce the level of methemoglobin in the blood. In severe cases, a person may require a blood transfusion or exchange transfusion. Oxygen therapy will also be provided, if required.

Which drug can cause methemoglobinemia?

Drugs that may cause Methemoglobinemia include nitrates derivatives (nitrates salt, nitroglycerin), nitrites derivatives (nitroprusside, amyl nitrite, nitric oxide), sulfonamides, dapsone, phenacetin, phenazopyridine, some local anesthetics such as prilocaine, topical anesthetics such as emla cream, benzocaine.

How do you get rid of methemoglobinemia?

Methylene blue is the primary emergency treatment for documented symptomatic methemoglobinemia. It is given in a dose of 1-2 mg/kg (up to a total of 50 mg in adults, adolescents, and older children) as a 1% solution in IV saline over 3-5 minutes.

What kind of disease is hereditary methemoglobinemia?

Disease definition. Hereditary methemoglobinemia (HM) is a rare red cell disorder classified principally into two clinical phenotypes: autosomal recessive congenital (or hereditary) methemoglobinemia types I and II (RCM/RHM type 1; RCM/RHM type 2, see these terms).

What happens when methemoglobin levels are elevated?

Increased levels of methemoglobin results in functional anemia. Methemoglobinemia is a condition with life-threatening potential in which diminution of the oxygen-carrying capacity of circulating hemoglobin occurs due to conversion of some or all of the four iron species from the reduced ferrous [Fe2+] state to the oxidized ferric [Fe3+] state.

What makes methemoglobin unable to release O2?

Methemoglobin (MetHb) is altered state of hemoglobin (Hb) in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of MetHb are UNABLE to bind oxygen (O2). Thus, oxygen dissociation curve is left-shifted, making it more difficult to release O2.

Is there any treatment for methemoglobinemia acquired form?

The condition is benign. There is no effective treatment for people with a congenital form who develop an acquired form. This means that they should not take drugs such as benzocaine and lidocaine. People who acquire methemoglobinemia from medications can completely recover with proper treatment.