Also known as blue baby syndrome, methemoglobinemia (congenital or acquired) is due to too much methemoglobin in the blood, which carries oxygen very poorly. What causes? An intoxication ? What symptoms?
What is the definition of methemoglobinemia?
Also called blue baby syndrome when it affects children, methemoglobinemia refers to a high level of methemoglobin in the blood. “In red blood cells, hemoglobin carries our oxygen. Methemoglobin is a derivative of hemoglobin which precisely transports oxygen very badly in the tissues.“, explains François Blanchecotte, president of the union of biologists. A normal methemoglobin level of 0.5 to 1% is present in everyone’s blood. Beyond this rate, the patient is in the context of methemoglobinemia.
As with the measurement of hemoglobin, it is necessary to carry out a blood test. The assay must be carried out quickly after the blood test because the methemoglobin level decreases by 10 to 20% every 8 hours. Biologists then use the spectrophotometric techniquethat is, the ability of methemoglobin to absorb light.
What causes methemoglobinemia?
There are two causes of methemoglobinemia:
- Congenital methemoglobinemia
- Acquired methemoglobinemia
What is congenital methemoglobinemia?
This form is due to a gene causes a deficiency of the enzyme NADH-cytochrome b5 reductase. This enzyme reduces methemoglobin and transforms it into hemoglobin. So, thanks to this enzyme, the methemoglobin level is now below 1.0%. In the case of congenital methemoglobinemia, the methemoglobin level can reach 20 to 45%.
What is acquired methemoglobinemia?
Acquired methemoglobinemia is contracted as a result of exposure to certain toxic products which cause oxidation of hemoglobin and transform it into methemoglobin. “These products can be certain drugs, local anesthetics, drugs like poppers, ant sprays, industrial cleaners, substances such as polyphenol, oxidizing agents imported by well water, fertilizermanure, some preservatives…“, lists our interlocutor.
What are the symptoms of methemoglobinemia?
Clinical signs appear when the methemoglobin level is greater than 10%.
► From 10%, the person affected has cyanosis: bluish spots appear on the skin and at the edge of the lips.
► Between 30 and 50% methemoglobinemia, signs of anoxia, lethargy, tachycardia, headaches and respiratory disorders appear.
► Above 50%the person may have brain damage, neurological disorders, respiratory distress.
► When the methemoglobin level reaches 70 to 85%death occurs.
Treatment: what to do in case of methemoglobinemia?
In the case of methemoglobinemia, whether inherited or acquired, doctors prescribe reducing compounds. It is most often about Vitamin C and methylene blue.
Thanks to François Blanchecotte, president of the union of biologists.