This condition develops when a person lacks sufficient healthy red blood cells in his blood. Oxygen is transported by these cells to different organs. If red blood cells also have deficiency of hemoglobin the body will not get enough oxygen. The low oxygen in blood results in anemia.
The normal hemoglobin levels are usually different for males and females. Anemia in men causes a hemoglobin level of lower than 13.5 gram/100ml. On the other hand, in women this level gets lower than 12.0 gram/100ml when anemia occurs.