Methaemoglobinaemia

Last updated: 06 October 2006

What is methaemoglobinaemia?

Methaemoglobinaemia is a very rare blood disorder where the blood is unable to carry oxygen to cells in the body. The condition occurs when normal haemoglobin, which is found inside red blood cells, is changed to abnormal haemoglobin, called methaemoglobin.

What are the symptoms

Symptoms of methaemoglobinaemia include:

• headache
• weakness
• nausea and vomiting
• diarrhoea
• increased heart rate
• breathlessness
• skin turning blue (called cyanosis)
• loss of consciousness.

In severe cases, the disease can be fatal. Symptoms usually occur rapidly after being exposed to some toxic substances.

What causes methaemoglobinaemia?

Methaemoglobinaemia is caused when a person is exposed to some poisons, including some types of drugs. Chemicals called nitrites have been known to cause methaemoglobinaemia after consumption. Rarely, some people have a genetic defect that causes the disease.

How is it diagnosed?

A person suffering methaemoglobinaemia is often very unwell. A blood test is needed to confirm the diagnosis. It is important that this condition is diagnosed early and treated promptly.

How is it treated?

Methaemoglobinaemia is treated using oxygen therapy and an antidote called methylene blue. People suffering with methaemoglobinaemia can make a full recovery with prompt treatment.

What can be done to avoid methaemoglobinaemia?

Outbreaks of methaemoglobinaemia have occurred when people have eaten food that has been contaminated with high levels of nitrites. People should not add any chemicals to food if they are uncertain of the ingredients.