Hemoglobin helps transport oxygen into the cells and carbon dioxide out. It is also a measure of how many red blood cells are in the blood. Normal hemoglobin ranges from 12 to 15 g/dL in women and 14 to 16.5 g/dL in men. Patients are followed more closely when levels drop below 10. The patient is very tired and may need a blood transfusion when levels drop below 8 d/dL.

Hemoglobin levels before an operation can help predict who might need a blood transfusion after surgery. Patients with low hemoglobin levels are at greater risk than patients with normal hemoglobin levels. Of course, a blood transfusion depends on how much (if any) blood was lost during the procedure.

Blood loss and transfusion usually means a longer stay in the hospital. On the other hand patients with good hemoglobin levels before coming into the hospital are more likely to go home sooner after surgery.