Chocolate-brown blood due to<unk>  Signs and symptoms of<unk>  <unk> moglobin level above 10%) include shortness of breath, cyanosis, mental status changes (~50%), headache, fatigue, exercise intolerance, dizziness, and loss of consciousness. People with severe<unk>  <unk> moglobin level above 50%) may exhibit seizures, coma, and death (level above 70%). Healthy people may not have many symptoms with<unk> moglobin levels below 15%. However, patients with co-morbidities such as anemia, cardiovascular disease, lung disease, sepsis, or presence of other abnormal hemoglobin species (e.g. carboxyhemoglobin, sulfhemoglobin or sickle hemoglobin) may experience moderate to severe symptoms at much lower levels (as low as 5–8%).
Methemoglobinemia
Argyria
Sulfhemoglobinemia
Heart failure
Hyperaemia
Hypoxemia
Organic acidemia
Hypercapnia