Methemoglobinemia
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Reason: Reason: Diagnosis missing
Under methemoglobinemia is understood in medicine, increased levels of methemoglobin (Met -Hb ) in the blood. The present in the red blood cell hemoglobin, which is used to transport oxygen is thereby converted into the inoperative methemoglobin ( oxidized, see methemoglobin ) and thus is not available for the transport of oxygen available.
Symptoms
Chronic methemoglobinemia often clinically silent run. In acutely occurring process it comes early to headache, fatigue, shortness of breath and lethargy. From a Met- Hb concentration of more than ten percent of the total hemoglobin it comes to hypoxemia (lack of oxygen in the blood) with cyanosis (blue discoloration of the skin and mucous membranes ). The blood gets a brownish-red color. For over forty percent it comes to dizziness, nausea, headache, increased heart activity, dyspnea, and somnolence ( drowsiness, sleepiness). A concentration of more than 70 to 80 percent results in death.
Causes
In addition to a hereditary defect in hemoglobin ( hemoglobin M disease) or a hereditary enzyme defect ( cytochrome b5 reductase deficiency ) is mainly the inclusion of certain substances that lead to oxidation of hemoglobin, cause of methemoglobinemia (toxic methemoglobinemia ). To oxidizing substances include some drugs ( phenacetin, quinine, lidocaine, prilocaine, metoclopramide, nitroglycerin, sulfonamides, etc.), oxides of nitrogen, aromatic nitro and amino compounds ( Popper, herbicides ) and others. Dangers exist for babies by the consumption of drinking water or vegetables with high nitrate levels. Numerous toxins lead to methemoglobinemia, among which are:
- Aniline dyes
- Antipyrine
- Chlorates
- Insecticides
- Sodium nitroprusside
- Sodium thiocyanate
- Nitrites
- Nitrobenzene
- Nitrobenzenes
- Nitroglycerin
- Phenacetin
- Sulfamethoxazole
- Sulfonamides
Diagnosis
At a drop of venous methemoglobinemia suspected patient's blood can be placed on a filter paper. Since methemoglobin can not be reduced by atmospheric oxygen, it remains brown, while normal hemoglobin in red colors by absorbing oxygen from the room air. It will have dropped next to the patient's blood to make a direct comparison in this very simple test is usually a drop of normal blood. In the blood smear Heinz bodies fall on in the erythrocytes, which represent the histological correlate of methemoglobin, as " clump " the Methämoglobinmoleküle speak in erythrocytes caused these precipitates. In the laboratory, a methemoglobinemia in EDTA blood or heparinized blood are detected.
Treatment
When toxic methemoglobinemia the triggering substance should be discontinued. Optionally methylene blue, toluidine blue or ascorbic acid may be administered. In hereditary causes no treatment is possible.