ABOUT RED BLOOD CELLS
Red blood cells (RBCs) give blood its colour. Their job is to carry oxygen from the lungs through the bloodstream to every part of the body. A substance in red blood cells called hemoglobin does this. Then, the red cells bring carbon dioxide (CO2) back to the lungs, where it’s removed from the body when we exhale.
Red blood cells (and all other blood cells) are normally made in the bone marrow, the soft inner part of certain bones. The production of RBCs is controlled by the kidneys. When the kidneys sense that there aren’t enough RBCs in the blood, they release a hormone called erythropoietin that causes the bone marrow to make more.
When red blood cell transfusions are used
Anaemia: People who have low numbers of red blood cells (RBCs) are said to have anaemia or be anaemic. People who have anaemia may need RBC transfusions because they don’t have enough RBCs to carry oxygen to all of the cells in the body. (Low iron or vitamin B12 levels are less common causes of anaemia in cancer patients.)
A normal hemoglobin level is about 12 to 18 g/dL. A person may need a red blood cell transfusion if the haemoglobin level drops below 8 g/dL. Whether you need a transfusion for anaemia depends on many factors, such as how long it took for the anaemia to develop and how well your body is able to cope with it. Anaemia due to a sudden loss of blood will probably need to be corrected right away. Anaemia that develops slowly is less likely to cause problems, because the body has time to adjust to it to some extent. If your hemoglobin level is lower than normal but you’re not dizzy, pale, or short of breath, you may not need a transfusion.
Patients who have certain heart or lung diseases may be more affected by anaemia and may need transfusions even if their hemoglobin level is not very low. Other conditions that increase the need for oxygen may also require transfusions.
There are drugs that can treat anaemia instead of a transfusion in some patients, but they carry different risks, work slowly, and cost a lot. For more information about anaemia and how it’s treated, see Anaemia in People With Cancer.
Surgery: Transfusions may be given during or after surgery to make up for blood loss. In some cases, blood lost during surgery can be collected and given back to the patient.