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URL of this page: //medlineplus.gov/ency/imagepages/19510.htm
Hemoglobin
Overview
Hemoglobin is the most important component of red blood cells. It is composed of a protein called heme, which binds oxygen. In the lungs, oxygen is exchanged 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 2/27/2026
Updated by: Jacob Berman, MD, MPH, Associate Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
