methæmoglobinæmi

Methæmoglobinæmia is a blood disorder characterized by an abnormally high level of methæmoglobin, a form of hemoglobin in which the iron atom is in the ferric (Fe3+) state rather than the usual ferrous (Fe2+) state. This oxidation of iron prevents hemoglobin from binding and transporting oxygen effectively to the body's tissues.

The condition can be congenital, arising from genetic mutations that affect the enzymes responsible for reducing methæmoglobin back to functional hemoglobin, or acquired. Acquired methæmoglobinæmia is more common and is typically caused by exposure to certain drugs, chemicals, or toxins. Examples include nitrates (found in contaminated water or certain foods), certain antibiotics like sulfonamides, local anesthetics such as benzocaine, and aniline dyes.

Symptoms of methæmoglobinæmia vary depending on the severity, with higher levels leading to more pronounced effects. Mild cases might present with bluish discoloration of the skin and mucous membranes (cyanosis), headache, and fatigue. More severe forms can result in shortness of breath, dizziness, rapid heart rate, confusion, seizures, and even coma or death if left untreated.

Diagnosis is made through blood tests that measure the level of methæmoglobin. Treatment for acquired methæmoglobinæmia usually involves administering methylene blue intravenously, which acts as an antidote by helping to convert methæmoglobin back to hemoglobin. In severe congenital cases, lifelong treatment or avoidance of trigger substances may be necessary.