Overview

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 — the blood disorder polycythemia vera, living at a high altitude, smoking and dehydration.

March 16, 2017
References
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  2. Longo DL, et al., eds. Disorders of hemoglobin. In: Harrison's Principles of Internal Medicine. 19th ed. New York, N.Y.: McGraw-Hill Education; 2015. http://accessmedicine.com. Accessed Nov. 27, 2016.
  3. CBC with differential, blood. Mayo Medical Laboratories. Rochester, Minn.: Mayo Foundation for Medical Education and Research. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9109. Accessed Nov. 27, 2016.
  4. Nicoll D, et al. Pocket Guide to Diagnostic Tests. 6th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com. Accessed Nov. 27, 2016.