Hemoglobin is a protein contained in red blood cells that carries oxygen to, and carbon dioxide away from, the body's cells. A hemoglobin test is typically ordered as part of a complete blood cell (CBC) count.
Higher than normal levels of hemoglobin may be caused by:
- Congenital heart disease.
- Cor pulmonale.
- Pedomonary fibrosis.
- Polycythemia vera.
- Increased red blood cell (RBC) production caused by an excess of erythopoeitin.
Low levels of hemoglobin may be a result of:
- Anemia.
- Erythropoetin deficiency.
- RBC destruction.
- Hemorrhaging (bleeding).
- Lead poisoning.
- Malnutrition.
- Iron, folate, vitamin B12 or vitamin B6 deficiency.
- Overhydration.
A blood sample will be taken, normally from the arm. If several tests are ordered, more than one vial of blood will be taken. If your hemoglobin has been low in the past, taking blood might seem counterproductive, but the CBC count can be a very useful tool to your physician in diagnosing and treating many health conditions.
Hemoglobin is measured in grams per deciliter of blood. The normal levels are:
- Women: 12.1 to 15.1 gm/dl
- Men: 13.8 to 17.2 gm/dl
- Children: 11 to 16 g/dl
- Pregnant women: 11 to 12 g/dl

