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.
Occurs when a sulfure atom is incorporated into the hemoglobin molecule.
Sulfide ions, derived from hydrogen sulfide, combine with the ferric ions of the hemoglobin molecule, this renders the iron containing heme group incapable of carrying oxygen.
The normal structure of Hemoglobin is shown below: