Hemoglobin is the most important component of red blood cells. It contains a protein called heme, which binds oxygen. In the lungs, oxygen enters the blood in exchange for carbon dioxide.Abnormalities of an individual's hemoglobin value can indicate defects in the normal balance between red blood cell production and destruction. Both low and high values can indicate disease states.
Review Date: 1/25/2013
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.