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Methemoglobinemia - Causes, Symptoms, Diagnosis, and Treatment

Published on Sep 09, 2020   -  4 min read



Methemoglobinemia is a blood disorder that can affect children. Read this article to know more about the causes, symptoms, and treatment.


What Is Methemoglobin?

Methemoglobin is a metalloprotein form of hemoglobin. It is not able to bind to the oxygen. It does not have enough capacity to carry oxygen. The normal range of methemoglobin is 0-3%. Higher levels of methemoglobin can reach up to 15%. When your body is producing too much of methemoglobin, it will start replacing the normally present hemoglobin. This can cause oxygen to be removed from the cells. The level of methemoglobin can be determined by blood cell count and examination of the color.

What Is Methemoglobinemia?

Methemoglobinemia is a blood disorder. An abnormal amount of methemoglobin is produced in this condition. Hemoglobin is the protein in red blood cells (RBCs) that carries and distributes oxygen to the body. In methemoglobinemia, the hemoglobin is still able to carry the oxygen but cannot release it efficiently to the tissues of the body.

What Are the Symptoms of Methemoglobinemia?

The symptoms might change based on the variant of methemoglobinemia. When the level of methemoglobin rises, symptoms begin to get worse. The common symptoms are:

Based on the concentration, the signs and symptoms shown may vary.

0-3 % - No symptoms will be shown.

10-20 % - Mild symptoms.

20-50 % - Decreased exercise tolerance, tachycardia, fatigue, and dyspnea.

Higher than 50 % - Seizure, hypoxia, coma, and metabolic acidosis.

Higher than 70 % - Severe hypoxia and death.

What Are the Types of Methemoglobinemia?

The acquired type is due to the problem in hemoglobin itself. The acquired type is more common than the inherited type. It is an acute condition.

What Are the Causes?

The acquired type occurs in some people due to the exposure of harmful chemicals and medicines. The commonly involved chemicals, food, and medications are:

What Are the Risk Factors?

The risk increases when the patient is suffering from comorbid conditions such as anemia, lung disease, sepsis, and cardiovascular disease. It is also associated with the presence of abnormal hemoglobin, such as sulfhemoglobin and sickle hemoglobin.

What Are the Complications?

How Is It Diagnosed?

  1. The Potassium Cyanide Test: This test is used for differentiating methemoglobin and sulfhemoglobin. When a few drops of potassium cyanide is added, methemoglobin turns to bright red, but sulfhemoglobin does not change color and remains dark brown.

  2. Clinical Examination: The characteristic chocolate brown color blood is noted.

  3. Blood Examination: Complete blood count is done to note the nitrates level in the blood and other drugs.

  4. Arterial Blood Gas Analysis: This is a method used to periodically check the saturation levels of oxygen, carbon-dioxide, and bicarbonate.

  5. Pulse Oximetry: This is used to identify the level of oxygen saturation in the blood. It is a non-invasive diagnostic method.

  6. DNA Sequencing: It is the process in which determining the nucleic acid sequence is done. It identifies the order of nucleotides in DNA molecules. It includes various technological methods to find the order of the four bases, such as adenine, guanine, cytosine, and thymine.

What Is the Treatment?

How Is the Prognosis?

The prognosis level decides the prediction level to show whether the condition will improve or not. The prognosis for methemoglobinemia is relatively very poor.

What Is the Differential Diagnosis?

Are you facing similar symptoms? Call a doctor online.


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Last reviewed at:
09 Sep 2020  -  4 min read


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