DefinitionBy Mayo Clinic staff
A hemoglobin test measures the amount of hemoglobin in your blood.
Hemoglobin is a protein in your red blood cells that carries oxygen to your body's organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs.
If a hemoglobin test reveals that your hemoglobin level is lower than normal, it means you have a low red blood cell count (anemia). Anemia can have many different causes, including vitamin deficiencies, bleeding and chronic diseases.
If a hemoglobin test shows a higher than normal level, there are several potential causes, such as the blood disorder polycythemia vera, living in a high altitude, smoking, dehydration, burns and excessive vomiting.
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- Laboratory reference values. Hematology group. Rochester, Minn.: Mayo Foundation for Medical Education and Research; February 2011.