Methemoglobinemia is an acquired or inherited blood disorder, in which
Methemoglobin, a nonfunctional form of
hemoglobin,
is present in red blood cells.
Methemoglobin is unable to bind oxygen reversibly because its iron is in the ferric form rather than in the ferrous form of
hemoglobin. Symptoms of the disorder are bluish skin, faintness, and shortness of breath. Severe anemia occurs because the blood loses the capacity to carry oxygen. Treatment includes administering vitamin C or methylene blue in order to convert methemoglobin to the functional hemoglobin.