What is Methemoglobinemia?

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  • Last Modified Date: 03 September 2019
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Methemoglobinemia or Met h-b is a rare blood disorder that may be caused by an inherited or congenital condition, exposure to toxins, especially nitrates, or dehydration, particularly in infants. In this condition, methemoglobin, a form of hemoglobin is present in too great a quantity. This particular type of hemoglobin cannot carry or bind oxygen, which means that the number of red blood cells containing oxygen is reduced. Poor supply of oxygen bearing red blood cells causes anemia, and can be disastrous to the organs, and when methemoglobin is present in large amounts, organs can begin to fail. Thus the condition can be fatal, causing total cardiac failure when it remains untreated.

Usually, methemoglobinemia is noticed prior to organ failure, especially in light-skinned people. It will cause cyanosis, distinctly blue skin. People who have this disorder look not just a little blue, but frequently very blue. Other symptoms include changes in mental status, confusion, shortness of breath, dizziness, and headaches. Continued build-up of methemoglobin can cause loss of consciousness, coma and eventually death. Diagnosis can be confirmed by checking the presences of methemoglobin in the blood, which should be less than 1%. Higher amounts confirm methemoglobinemia. Further, blood from arteries looks brown instead of bright red.


The condition is treatable, and may need to be retreated in people who have congenital or inherited methemoglobinemia by attempting to reduce methemoglobin so that the iron molecules will again carry oxygen. This is normally accomplished through intravenous drips of the substance methylene blue. As treatment progresses, skin begins to pink up and the body’s major organs are better oxygenated.

While methemoglobinemia may be inherited, incidence of inheritance is low. Instead, the disease normally manifests after severe dehydration or exposure to toxins. In a 2007 episode of the spin-off show of Grey’s Anatomy, Private Practice, several sisters developed the condition after long exposure to nitrate fertilizers. This is actually a perfect example of how certain toxins can create the condition.

Infants, especially those less than six months old, are also very vulnerable to methemoglobinemia if they get illnesses that result in dehydration. Young children are especially prone to dehydration from diarrhea or vomiting because their body weight is so low. Unlike adults, they can become dehydrated within a few hours of getting ill, which can create excess levels of methemoglobin quickly. This is why it is extremely important to treat young children with severe diarrhea or vomiting immediately, especially if the condition doesn’t resolve within a few hours, and the child cannot tolerate or keep down any fluids.


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Post 2

We are a family where many of us have a variant of this but suffer no major ill effects.

Post 1

My daughter has methemoglobinanemia IWADA variant. She was born with it. Her father, aunt and 1st cousins have it, her grandfather and great uncle and 2nd cousin have it, her great grandfather had it and her great great grandmother had it.

I am told that a study was done on the family in san francisco somewhere, but I can not find anything published. She was born blue taken away at birth to rule out pulmonary problems and returned to me with little or no problems than some people asking her why her lips are blue. When she is sick she is bluer that usual and under fluorescent lights she looks like death. But all and all she is a happy

and healthy 10 year old kid. But what happens is when she gets into respiratory trouble she tanks and she tanks fast.

What i am trying to find out is what is a baseline plus ox for these blue folks and at what point do you start to worry? We went to the dr for a cold and fever which turned out to be pneumonia and the doc who saw us was not our doc and very few docs have seen this clinically so they do not know what to do and suddenly they are recommending all kinds of silly things that have no effect. Hematologists are like yea there is nothing you can do for it there is no cure blah blah. My in-laws said it is common in Portuguese people but when i read articles on the net they seem to say the same thing and they clump the acquired and congenital forms in the same basket and they are not. Congenital forms do not respond to methyl blue dye. I am at a loss here and would like to get some answers if it is common for other folks who have this disorder to tank when they get into respiratory problems and what is an acceptable pulseox for a methemoglobinanemia patient.

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