Anemia is a condition that occurs when the blood does not contain enough red blood cells.
Red blood cells carry oxygen from the lungs to the body’s tissues. In a healthy person, the body sends signals to the bone marrow to create more red blood cells whenever the body needs more oxygen. A hormone called erythropoietin, produced in the kidney, is the signal that stimulates the bone marrow to produce red blood cells. When the body does not produce enough erythropoietin, fewer red blood cells are produced, and therefore less oxygen is delivered to the body.

Certain diseases--such as cancer and chronic kidney disease--are related to anemia. Cancer patients undergoing chemotherapy often suffer from anemia because chemotherapy attacks not only cancerous cells, but other cells in the body as well, including red blood cells. In kidney disease patients, kidney function is reduced. Erythropoetin, the body’s signal that tells bone marrow to make more red blood cells, comes from the kidneys, so in these patients, fewer red blood cells are produced.

Some common symptoms of anemia include: fatigue, weakness, rapid heart beat, shortness of breath, dizziness or fainting, feeling cold, sadness or depression, and shortness of breath. Anemia can strain the heart as it overworks to deliver oxygen throughout the body. It also can make certain cancer therapies less effective and can interrupt chemotherapy treatment. If left untreated, anemia can result in the need for red blood cell transfusions.