Symptoms
As already mentioned, the presence of methemoglobin in the blood is normal to a certain extent. Approximately 1.5% of the hemoglobin content is formed by methemoglobin. From a quantity of approx.
10%, symptoms of oxygen deficiency occur. The so-called cyanosis becomes visible in the colour of the skin, which appears greyish to bluish. If the proportion is even higher, at about 30%, the blood takes on a brownish colour.
The oxygen saturation is then no longer sufficient. A feeling of weakness, shortness of breath, dizziness and unconsciousness may occur. From a methaemoglobin content of approx. 60%, this condition is life-threatening. This is a kind of internal suffocation, as the oxygen is available in principle, but cannot be transported by the red blood cells.
Therapy
An antidote for methemoglobinemia is methylene blue. Provided that all enzymes are present in sufficient quantities, it leads to a chemical reaction in the body in which it is converted into a substance capable of converting methaemoglobin into haemoglobin. If methylene blue is not available or its effect is insufficient, there is still the possibility of a blood transfusion. In this case, the blood containing the toxic methaemoglobin is exchanged for “healthy” blood.
Forecast
The prognosis depends on the amount of methaemoglobin in the blood and the timely initiation of therapy. If the symptoms are mild and the methaemoglobin content rather low, a therapy with methylene blue can restore the physiological state of the blood. However, since many body cells, especially cells of the brain, cannot survive for long without sufficient oxygen, too high a proportion of meth haemoglobin can quickly become life-threatening. If an efficient therapy is not initiated within minutes in this state, permanent damage may remain.
Course of disease
The course of the disease depends on the amount of methaemoglobin in the blood. Symptoms of oxygen deficiency occur from a proportion of about 10%. It can lead to lack of concentration, headaches and dizziness. If the proportion continues to rise, dizziness and a clouding of consciousness up to unconsciousness usually result. If no adequate therapy is initiated at this time and the methaemoglobin level continues to rise, a methaemoglobin level of 60% or higher can be fatal.
How contagious is it?
Methemoglobinemia is not a contagious disease.
