Anemia can be defined as a low red blood cell count. Too few red blood cells can affect the ability of the blood to deliver oxygen-rich blood to the tissues. A normal red blood cell count is measured by hemoglobin which is the component of red cells that carries oxygen. Since oxygen keeps your cells alive and functioning, a sufficient supply of red blood cells is vital to staying alive. Normal hemoglobin range for men is 13.5 to 17.5 g/dL. A normal hemoglobin range for women is 12 -16 g/dL. Anemia can be caused by certain chronic illnesses, heavy menstrual bleeding and malignancy.
Years ago physicians were taught that a certain minimum level of hemoglobin was necessary. It was generally thought that unless apatient had a hemoglobin of 10 g/dL it was unsafe to operate on that patient. The emergence of bloodless medicine as a new medical discipline reflects the current medical philosophy that patients can survive much lower blood counts than traditionally thought. Today phsycians understand that the individual patient's condition should be the biggest facctor in considering the need for a red cell transfusion. Most recently, clinicians are realizing that there really is no absolute number at which a patient needs to be transfused.