There is too much methemoglobin in the blood, a form of hemoglobin that cannot carry oxygen, resulting in methemoglobinemia. There are various symptoms and complications associated with low oxygen levels in the body. Methemoglobinemia can be inherited or acquired, depending on its cause. Medication, oxygen therapy, or blood transfusions can be used to treat it. By avoiding or limiting exposure to substances that increase methemoglobin levels, methemoglobinemia can be prevented.
Causes of Methemoglobinemia
There are a variety of factors that can affect methemoglobin levels in the blood and result in methemoglobinemia. These factors include:
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There are two types of inherited methemoglobinemia: type 1 and type 2. Type 1 affects only the red blood cells and causes mild symptoms. It is a rare genetic disorder that affects the enzyme that converts methemoglobin back to normal hemoglobin. All cells are affected by type 2, resulting in severe symptoms and developmental difficulties.
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It occurs when a person is exposed to certain substances that increase methemoglobin levels, such as:
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Medications, such as nitrites, nitrates, sulfonamides, anesthetics, or dapsone.
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Benzene, aniline, or nitrobenzene are chemicals.
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Spinach, beets, and celery are vegetables that contain nitrates.
Symptoms of Methemoglobinemia
Symptoms of methemoglobinemia depend on the level of methemoglobin in the blood. Usually, the level of methemoglobin is less than 1%. When the level exceeds 10%, symptoms may appear.
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A low oxygen level causes cyanosis, which is a bluish or grayish color on the skin, lips, or nails.
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Methemoglobin gives blood a chocolate-brown color.
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Low oxygen levels can cause headaches, fatigue, weakness, or dizziness.
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As a result of low oxygen levels, you may experience shortness of breath, chest pain, or palpitations.
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As a result of low oxygen levels, you may experience nausea, vomiting, or abdominal pain.
Symptoms may become life-threatening when methemoglobin levels reach 50% or higher, such as:
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Low oxygen levels in the brain can cause confusion, seizures, or comas.
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Low oxygen levels in the tissues cause metabolic acidosis, which causes the blood to become too acidic.
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Low oxygen levels in the organs cause heart, lung, liver, or kidney failure.
Diagnosis of Methemoglobinemia
The doctor will perform a physical examination and ask about the person's medical history and symptoms, as well as order some tests to measure methemoglobin levels and oxygen saturation in the blood.The doctor will perform a physical examination and ask about the person's medical history and symptoms. The doctor may order some tests to measure methemoglobin levels and oxygen saturation in the blood. These tests include:
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The arterial blood gas (ABG) test measures the pH, the partial pressure of oxygen (PaO2), the partial pressure of carbon dioxide (PaCO2), and the level of bicarbonate (HCO3) in the blood. A low PaO2, a low oxygen saturation, and a high methemoglobin level indicate methemoglobinemia.
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The co-oximetry test measures the levels of different types of hemoglobin in the blood, including oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin.
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Tests that analyze DNA can identify inherited methemoglobinemia by looking for mutations or defects in the gene that codes for the enzyme that reduces methemoglobin.Tests that analyze DNA can identify inherited methemoglobinemia by looking for mutations or defects in the gene that codes for the enzyme that reduces methemoglobin.
Treatment of Methemoglobinemia
Methemoglobinemia can be treated according to its cause, level, and symptoms. Treatment options include:
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An important medication for treating methemoglobinemia is methylene blue, a dye that aids the enzyme in converting methemoglobin to normal hemoglobin. In minutes, methylene blue can reduce the methemoglobin level intravenously (through a vein). People with methemoglobinemia or glucose-6-phosphate dehydrogenase (G6PD) deficiency, a condition that affects the red blood cells, cannot benefit from methylene blue. Ascorbic acid (vitamin C) or N-acetylcysteine may be used in these cases.
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Through a mask, tube, or chamber, oxygen is administered to the patient as part of oxygen therapy. In addition to increasing the oxygen levels in blood and tissues, oxygen therapy can reduce the symptoms of methemoglobinemia. Oxygen therapy can be used alone or in conjunction with medication.
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Blood transfusion: Blood transfusions are treatments in which people receive blood from a donor. During a blood transfusion, methemoglobin can be replaced with normal hemoglobin and oxygen levels can be restored. When medication and oxygen therapy are not sufficient to treat severe cases of methemoglobinemia, blood transfusions are usually reserved.
Prevention of Methemoglobinemia
By avoiding or limiting exposure to substances that can increase methemoglobin levels, such as drugs, chemicals, or foods, methemoglobinemia can be prevented or reduced.
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Be sure to read the labels and instructions of any medications or products that may contain methemoglobin-inducing substances and follow their dosage and usage instructions
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Keep medications and products that may contain methemoglobin-inducing substances out of children's and pets' reach, and store them safely and properly
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It is important to wash fruits and vegetables that may contain nitrates thoroughly before eating them, and to avoid eating them in large quantities or frequently.
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Medical attention should be sought if you experience any symptoms of methemoglobinemia, such as cyanosis, headaches, or shortness of breath
