Methemoglobinemia is a pathological condition, due to increased levels of methemoglobin in the blood above 1%, that leads to tissue hypoxia due to its inability to transport oxygen. Congenital forms of this disease most common among residents of Greenland, Alaska, Yakutia and Navajo (United States). Acquired forms often arise from poisoning in the workplace.
Hereditary (congenital) the form of this pathology due, usually, or m-gemoglobinopatijami, in which abnormal proteins are synthesized, contain oxidized iron trjohvalentnoe (autosomal dominant inheritance), or fermentopatijami, where metgemoglobin reductase has a low activity or non-existent (Pathology data inherit autosomal disease type). Acquired (secondary) natal exogenous origin occur in overdose some medicines (nitritami, lidokainom, sulьfanilamidami, novocaine, antimalarial drugs, vikasolom) or poisoning by chemicals (trinitrotoluolom, aniline dyes, chlorobenzene, silver nitrate, Food and water, contain large amounts of nitrates). Acquired methemoglobinemia often develop endogenous in infants with metabolic azidoze, viral and bacterial enterocolitis, diarejnom syndrome. If a healthy person, is geterozigotnym a carrier of genes of hereditary methemoglobinemia, ill this pathology as a result of exposure to exogenous factors, then talk about the mixed form of methemoglobinemia.
If there is a form of congenital methemoglobinemia clinical manifestations are determined from birth. Intact skin and mucous membranes cianotichny these children (especially in the area of nasolabial triangle, polish, conjunctiva, ear lobes), lag behind in physical and mental development. Later complaints appear on Vertigo, headache, drowsiness, taxikardiju, rapid fatigability, and the emergence of breathlessness.
Acquired methemoglobinemia methemoglobin concentrations less than 3% may not have clinical manifestations. With methemoglobin to 15% appears grayish skin, at 15-30% – кровь приобретает шоколадный оттенок, cyanosis appears, with methemoglobin to 50% fainting may occur, headaches and dizziness, weakness, shortness of breath and tachycardia, with increasing content of methemoglobin in the blood more 50% metabolic acidosis develops, cramps can occur, Arrhythmia, confusion and even coma. Concentration of methemoglobin in the blood more 70% is considered deadly.
In the diagnosis of methemoglobinemia are used the following methods of laboratory and instrumental studies:
The following congenital methemoglobinemia: congenital insufficiency of NADH-metgemoglobinreduktazy, hereditary methemoglobinemia, gemoglobinoz m. Acquired methemoglobinemia are divided into toxic exogenous and endogenous. According to some sources there is a mixed form of methemoglobinemia.
When it encounters a host or child symptoms, similar to above, It is recommended to consult a specialist for qualified help.
In order to restore normal hemoglobin in severe cases prescribed oxygen, bed rest, ascorbic acid (500-1000 mg / day), kardiotonicheskie medicines, 1% methylene blue solution (hromosmon) the rate of 1-2 mg/day 40% glucose tolerance, lobelia or cititon. In Natal, accompanied by sul'fgemoglobinemiej, conduct exchange transfusion.
Natal complication is hypoxia tissue, and in severe cases, death (When the level of methemoglobin more 70%).
Prevention of the development of acquired forms metgemoglobinemij is avoiding exposure to metgemoglobinobrazujushhih substances. Prevention of congenital forms of genetic counselling is considered when planning pregnancy.
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