Definition

A low hemoglobin count is a commonly seen blood test result. Hemoglobin (Hb or Hgb) is a protein in red blood cells that carries oxygen throughout the body.

A low hemoglobin count is generally defined as less than 13.5 grams of hemoglobin per deciliter (135 grams per liter) of blood for men and less than 12 grams per deciliter (120 grams per liter) for women. In children, the definition varies with age and sex. The threshold differs slightly from one medical practice to another.

In many cases, a low hemoglobin count that's only slightly lower than normal doesn't affect how you feel. A low hemoglobin count that's more severe and causes symptoms might mean you have anemia.