Table of ContentsView AllTable of ContentsCausesSymptomsInherited FormAcquired FormDiagnosisTreatmentPreventionFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Causes
Symptoms
Inherited Form
Acquired Form
Diagnosis
Treatment
Prevention
Frequently Asked Questions
Methemoglobinemiais an uncommon medical condition that makes some of the red blood cells unable to transport oxygen. Symptoms can range from absent to mild to life-threatening.
Usually, methemoglobinemia results from certain toxins or overexposure to certain drugs, like someanesthetics(drugs used to reduce pain and sensation). A smaller number of people also have methemoglobinemia due to genetic problems present from birth.
This article will discuss some of the causes and symptoms of methemoglobinemia, as well as its diagnosis, treatment, and related issues.
Arindam Ghosh / iStock / Getty Images Plus
Methemoglobinemia Causes
Your red blood cells contain an important protein calledhemoglobin. In its normal state, this protein transports life-giving oxygen to all the cells of your body. Specifically, iron in the hemoglobin picks up oxygen that is taken around the body. Hemoglobin also gives blood its reddish color.
Methemoglobin is a form of hemoglobin that is a little different from normal hemoglobin. Because of a slight difference in the form of iron it contains, it can’t pick up oxygen normally, so it can’t take it to parts of the body that need it.
Methemoglobin is usually present at low levels in the body (less than 1% of total hemoglobin). However, when this percentage increases, it can cause problems. In methemoglobinemia, at least 3% or more of a person’s hemoglobin is in the form of abnormal methemoglobin.
Who Is at Risk?Methemoglobinemia can result from genetic problems (this is called inherited methemoglobinemia), or something in the environment might change the configuration of some of a person’s hemoglobin to methemoglobin (acquired methemoglobinemia).People with certain health conditions, like lung disease, heart disease, oranemia(lack of healthy red blood cells) also have an increased risk of developing methemoglobinemia.
Who Is at Risk?
Methemoglobinemia can result from genetic problems (this is called inherited methemoglobinemia), or something in the environment might change the configuration of some of a person’s hemoglobin to methemoglobin (acquired methemoglobinemia).People with certain health conditions, like lung disease, heart disease, oranemia(lack of healthy red blood cells) also have an increased risk of developing methemoglobinemia.
Methemoglobinemia can result from genetic problems (this is called inherited methemoglobinemia), or something in the environment might change the configuration of some of a person’s hemoglobin to methemoglobin (acquired methemoglobinemia).
People with certain health conditions, like lung disease, heart disease, oranemia(lack of healthy red blood cells) also have an increased risk of developing methemoglobinemia.
Methemoglobinemia Symptoms
If you have only a little more methemoglobin in your blood than normal, you might not notice any symptoms.
Because the body does a good job of compensating, people with mild, chronic methemoglobinemia might only learn of it when undergoing medical tests for other reasons. Sometimes methemoglobinemia only becomes apparent when a person is experiencing other problems, like recovering from surgery in the intensive care unit (ICU).
In contrast, if you have a higher percentage of methemoglobin, you could have life-threatening issues.
Some possible symptoms are:
With severe methemoglobinemia, symptoms might include:
Death is also possible in severe situations.
Inherited Forms of Methemoglobinemia
People withtype 1congenital methemoglobinemia often have an average lifespan and don’t experience complications.
The affected gene intype 2inherited methemoglobinemia leads to a problem with a protein (called cytochrome 5 reductase). This protein helps keep the iron in the right configuration for regular hemoglobin (and not methemoglobin).
People with type 2 congenital methemoglobinemia have a severe problem with this protein. Because of this, symptoms are most severe for people with type 2 congenital methemoglobinemia. Most people with type 2 die in infancy. They also tend to have developmental delays and other neurological issues.
Other congenital disorders can also cause increased levels of methemoglobin. These include:
Acquired Methemoglobinemia
Exposure to certain drugs or toxins can also trigger methemoglobinemia in some people. Some examples are:
However, not everyone exposed to these substances develops methemoglobinemia. Some people have a greater tendency toward developing it than others.
Warning on Teething ProductsBecause of the risks of methemoglobinemia, the Food and Drug Administration (FDA) recommends against using over-the-counter teething products that include benzocaine (e.g., Orajel) in children younger than 2.Silicone teething rings are a good alternative.Learn More:A Guide to Infant Teething
Warning on Teething Products
Because of the risks of methemoglobinemia, the Food and Drug Administration (FDA) recommends against using over-the-counter teething products that include benzocaine (e.g., Orajel) in children younger than 2.Silicone teething rings are a good alternative.Learn More:A Guide to Infant Teething
Because of the risks of methemoglobinemia, the Food and Drug Administration (FDA) recommends against using over-the-counter teething products that include benzocaine (e.g., Orajel) in children younger than 2.Silicone teething rings are a good alternative.
Learn More:A Guide to Infant Teething
Experts: Nitrate Water Contamination Is Now a Public Health Threat
A person’s symptoms, medical history, and physical exam results all provide important clues to consider methemoglobinemia. Certain medical tests also give key information. Some of these might be:
These all give information about the oxygenation status within your blood. The latter is less accurate, but unlike the others, you don’t have to directly access a person’s blood. Pulse oximetry screening can also sometimes help identify infants born with methemoglobinemia.
Other tests may also be necessary to rule out other more common causes of a person’s symptoms related to low oxygen (hypoxia).
Hypoxia Can Lead to Oxygen Starvation of the Tissues
Unlike most other people showing symptoms from poor levels of oxygen, people with methemoglobinemia don’t improve when given pure oxygen to breathe. This can be a clue that methemoglobinemia might be the problem.
Because methemoglobinemia is relatively rare but often reversible, it’s especially important that healthcare providers consider it as a possibility.
Additional testing, such as genetic tests, may be needed for inherited forms of the disease.
Treatment can vary based on the severity of methemoglobinemia, whether it is a sudden or chronic issue, and whether it is from exposure or a genetic cause. Severe methemoglobinemia requires immediate emergency treatment, but someone who has chronic mild methemoglobinemia may not need any treatment at all.
Some potential treatments include:
ComplicationsIf promptly diagnosed and treated, people with acquired methemoglobinemia typically completely recover without complications.
Complications
If promptly diagnosed and treated, people with acquired methemoglobinemia typically completely recover without complications.
People who have inherited forms of methemoglobinemia should avoid drugs known to trigger methemoglobinemia in some people. Information regarding this should be available on the drug’s labeling information. Even if you’ve never had symptoms from it yourself, this information may be important if someone in your family has ever had such a problem.
When starting new medications or considering surgery, discuss this complete medical history with your healthcare provider. You might need a different medication, or your surgical team may need to take additional precautions.
Summary
A Word From Verywell
It can be frightening to learn that you or a loved one has methemoglobinemia. The good news is that we have excellent treatments for acquired methemoglobinemia, even though its initial symptoms might be serious. Also, most people with inherited disease have a subtype with manageable symptoms and an average life span.
Frequently Asked QuestionsMethemoglobinemia is met·HEE·muh·glow·buh·NEE·mee·uh. The protein itself is methemoglobin, pronounced met·HEE·muh·glow·bin.This depends on the severity of your exposure, the promptness of treatment and diagnosis, and your other medical conditions. However, symptoms usually go away within a few hours or less of receiving treatment with methylene blue.
Methemoglobinemia is met·HEE·muh·glow·buh·NEE·mee·uh. The protein itself is methemoglobin, pronounced met·HEE·muh·glow·bin.
This depends on the severity of your exposure, the promptness of treatment and diagnosis, and your other medical conditions. However, symptoms usually go away within a few hours or less of receiving treatment with methylene blue.
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Trivedi DJ, Joshiraj B, Bidkar V, Rao R.Methemoglobinemia: Living with dormant devil.Indian J Clin Biochem. 2017;32(2):248-250. doi:10.1007/s12291-016-0586-5
Viršilas E, Timukienė L, Liubšys A.Congenital methemoglobinemia: Rare presentation of cyanosis in newborns.Clin Pract. 2019;9(4):1188. doi:10.4081/cp.2019.1188
Ponce Ríos JD, Yong R, Calner P.Code blue: Life-threatening methemoglobinemia.Clin Pract Cases Emerg Med. 2019;3(2):95-99. doi:10.5811/cpcem.2019.3.41794
US Food and Drug Administration.Risk of serious and potentially fatal blood disorder prompts FDA action on oral over-the counter benzocaine products used for teething and mouth pain and prescription local anesthetics.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
