Hemoglobin

An iron-containing protein in red blood cells that binds oxygen and helps transport it from the lungs to tissues throughout the body.

Hemoglobin is responsible for much of the oxygen-carrying capacity of blood. It also contributes to the transport of carbon dioxide and helps buffer acids in the blood.

Hemoglobin concentration is commonly measured as part of a complete blood count (CBC). A low hemoglobin concentration is a key feature of anemia, although anemia has many possible causes.

COMMONLY CONFUSED WITH

  • Red blood cell: the cell that contains hemoglobin; hemoglobin is a protein inside the cell.
  • Hematocrit: the proportion of blood volume occupied by red blood cells, not the amount of hemoglobin itself.
  • Anemia: a condition involving inadequate oxygen-carrying capacity of blood, commonly associated with low hemoglobin.

SEE ALSO

Clinical & Educational Context

Discussed in Health Articles & Guides

Explore how "Hemoglobin" is covered across our evidence-based editorial guides:

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The Hard Parts of Medicine

Do You Need Supplements? What Medical Research Says

For example: Iron is needed to produce hemoglobin, the protein in red blood cells that carries oxygen.