Methemoglobin

Methemoglobin is a form of hemoglobin, the protein in red blood cells that carries oxygen. Normally, hemoglobin contains iron in a ferrous (Fe²⁺) state, allowing it to bind oxygen effectively. In methemoglobin, the iron is in a ferric (Fe³⁺) state, which cannot carry oxygen. When too much methemoglobin forms, it reduces the blood’s ability to deliver oxygen to tissues, leading to symptoms like skin discoloration (bluish tint) and breathlessness. This condition can be caused by certain medications, chemicals, or inherited factors, and is typically treatable once identified.