Methemoglobinemia history and symptoms

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Congenital (Hereditary) Methemoglobinemia

There are three main congenital conditions that lead to methemoglobinemia:

1. Cytochrome b5 reductase deficiency and pyruvate kinase deficiency

2. G6PD deficiency

3. Presence of abnormal hemoglobin.

Acquired or Acute Methemoglobinemia

Most common cause include different oxidant drugs, toxins or chemicals

History and Symptoms

Signs and symptoms of methemoglobinemia (methemoglobin >1%) include shortness of breath, cyanosis, mental status changes, headache, fatigue, exercise intolerance, dizziness and loss of consciousness. Arterial blood with elevated methemoglobin levels has a characteristic chocolate-brown color as compared to normal bright red oxygen containing arterial blood.

Severe methemoglobinemia (methemoglobin >50%) patients have dysrhythmias, seizures, coma and death. Healthy people may not have many symptoms with methemoglobin levels < 15%, however patients with co-morbidities such as anemia, cardiovascular disease, lung disease, sepsis, or presence of other abnormal hemoglobin species (e.g. carboxyhemoglobin, sulfehemoglobin or sickle hemoglobin) may experience moderate to severe symptoms at much lower levels (as low as 5-8%).