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Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. [2] Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). [2] Complications may include seizures and heart arrhythmias. [3][4]
Methemoglobin. The structure of cytochrome b5 reductase, the enzyme that converts methemoglobin to hemoglobin. [1] Methemoglobin (British: methaemoglobin, shortened MetHb) (pronounced "met-hemoglobin") is a hemoglobin in the form of metalloprotein, in which the iron in the heme group is in the Fe 3+ (ferric) state, not the Fe 2+ (ferrous) of ...
In such cases, the enzyme methemoglobin reductase will be able to eventually reactivate methemoglobin by reducing the iron center. In adult humans, the most common hemoglobin type is a tetramer (which contains four subunit proteins) called hemoglobin A , consisting of two α and two β subunits non-covalently bound, each made of 141 and 146 ...
A methemoglobin level > 1.5 g/dL causes cyanosis. The most common congenital cause is a deficiency in the enzyme cytochrome b5 reductase which reduces methemoglobin in the blood. [22] However, in infants the most common cause of methemoglobinemia is acquired through the ingestion of nitrates (NO − 3) through well water or foods.
Hemoglobinemia (or haemoglobinaemia) is a medical condition in which there is an excess of hemoglobin in the blood plasma. This is an effect of intravascular hemolysis, in which hemoglobin separates from red blood cells, a form of anemia. Hemoglobinemia can be caused by intrinsic or extrinsic factors. When hemoglobinemia is internally caused ...
The oxygen–hemoglobin dissociation curve, also called the oxyhemoglobin dissociation curve or oxygen dissociation curve (ODC), is a curve that plots the proportion of hemoglobin in its saturated (oxygen-laden) form on the vertical axis against the prevailing oxygen tension on the horizontal axis. This curve is an important tool for ...
Methylene blue is employed as a medication for the treatment of methemoglobinemia, which can arise from ingestion of certain pharmaceuticals, toxins, or broad beans in those susceptible. [11] Normally, through the NADH- or NADPH-dependent methemoglobin reductase enzymes, methemoglobin is reduced back to hemoglobin. When large amounts of ...
Sulfhemoglobinemia. Sulfhemoglobinemia is a rare condition in which there is excess sulfhemoglobin (SulfHb) in the blood. The pigment is a greenish derivative of hemoglobin which cannot be converted back to normal, functional hemoglobin. It causes cyanosis even at low blood levels. It is a rare blood condition in which the β-pyrrole ring of ...