Low red blood cell count (anemia)

Anemia is a condition caused by a low level of healthy red blood cells (RBCs). Cancer and its treatment can lower the number of RBCs and the hemoglobin level in the blood. Hemoglobin is the part of the red blood cell that carries oxygen. When hemoglobin levels are low, body tissues don’t get enough oxygen and can’t work properly.

Normal levels of RBCs and hemoglobin vary for men, women and children. They also vary from laboratory to laboratory.

Normal RBC and hemoglobin levels

Red blood cell count

Hemoglobin levels

Men 4.6–6.2 x 1012/L 120–160 g/L
Women 4.2–5.1 x 1012/L 120–160 g/L
Children 4.1–5.4 x 1012/L 115–135 g/L

An adult has anemia, or is considered anemic, when their hemoglobin level falls to about 100g/L or less. A child has anemia if the hemoglobin is 75 g/L or less. Symptoms of anemia may develop even if the hemoglobin is higher than these levels.


Anemia can be caused by:

  • lower RBC production
  • destruction of RBCs
  • blood loss due to too much bleeding
  • malnutrition
  • low levels of iron, vitamin B12 or folic acid
  • some chronic diseases such as kidney disease

Cancer or cancer treatment (such as chemotherapy or radiation therapy) can affect the bone marrow so that it doesn’t make enough healthy red blood cells.

Each type of blood cell lives for a certain amount of time. The body constantly breaks down and replaces red blood cells. Certain diseases or immune system reactions to blood cells can speed up this process so too many red blood cells are destroyed.


Symptoms of anemia can vary. It tends to develop slowly in people receiving cancer treatments. A variety of symptoms can occur when hemoglobin levels are low and body tissues don’t get enough oxygen.

Symptoms of anemia include:

  • fatigue
  • lack of energy
  • malaise
  • pale skin, especially noticeable around the lips and nail beds
  • dizziness
  • weakness
  • shortness of breath
  • increased or irregular heart rate
  • low blood pressure
  • chest pain
  • feeling cold or chilled
  • headache
  • poor appetite
  • difficulty concentrating


Your doctor will try to find the cause of anemia. This may include asking questions about your symptoms and medicines and treatments you are taking. Your doctor may also do a physical exam.

You may need to have the following tests:

  • Blood tests are used to check the level of RBCs, hemoglobin, hematocrit, iron and vitamin B12.
  • Bone marrow aspiration and biopsy may be done to find out what is causing anemia if other tests don’t show any abnormalities.

Managing anemia

Once the cause of anemia is known, your healthcare team can suggest ways to treat it. Treatments will depend on the cause of anemia.


Your doctor may prescribe medicines to help correct low levels of iron, vitamin B12 or folic acid. Take iron pills or other medicines as prescribed by your doctor.

Blood transfusions

You may need blood transfusions to relieve symptoms such as shortness of breath. More than one blood transfusion may be needed to correct the underlying cause of anemia. They may be given until the bone marrow can replace RBCs.

Colony-stimulating factors (CSFs)

Colony-stimulating factors are special medicines (growth factors) that stimulate the bone marrow to make red blood cells.

Erythropoietin is a hormone made by the kidney. It is involved in making red blood cells. The drugs epoetin alfa (Eprex, erythropoietin) and darbepoetin (Aranesp) are erythropoietin products that may be given to treat anemia. These drugs increase RBC production so that people with anemia may not need blood transfusions. They improve the quality of life for many people with anemia related to cancer. These drugs don’t work as quickly as a blood transfusion. It may take 2–8 weeks before someone starts to benefit from CSF treatment. However, the body’s response to these drugs usually lasts longer than a blood transfusion.


Get plenty of rest to keep up energy levels and help you cope with anemia and its effects.

Avoid strenuous or long periods of activity. Schedule rest breaks throughout the day. Prioritize activities and do those that are most important.

Move slowly to avoid getting dizzy. When you get out of bed, sit on the side of the bed for a while before standing up.

Eat a balanced diet that includes foods high in iron. These foods include green leafy vegetables, liver and cooked red meats.

Expert review and references

  • Understanding chemotherapy: a guide for patients and families. American Cancer Society. American Cancer Society. American Cancer Society; 2013.
  • Anemia. American Society of Clinical Oncology (ASCO). Cancer.Net. Alexandria, VA.: American Society of Clinical Oncology (ASCO); 2009.
  • Camp-Sorrell, D . Chemotherapy toxicities and management. Yarbro, CH, Wujcki D, & Holmes Gobel B. (eds.). Cancer Nursing: Principles and Practice. 7th ed. Sudbury, MA: Jones and Bartlett; 2011: 17: pp. 458-503.
  • Haas ML . Radiation therapy: toxicities and management. Yarbro, CH, Wujcki D, & Holmes Gobel B. (eds.). Cancer Nursing: Principles and Practice. 7th ed. Sudbury, MA: Jones and Bartlett; 2011: 14: 312-351.
  • Hockenberry MJ, Kline NE . Nursing support of the child with cancer. Pizzo, P. A. & Poplack, D. G. (Eds.). Principles and Practice of Pediatric Oncology. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2011: 43:1288-1304.
  • Hospital for Sick Children. AboutKidsHealth: Side Effects of Chemotherapy. Toronto, ON: Hospital for Sick Children; 2009.
  • Panzarella C, Rasco-Baggott C, Comeau, M., et al . Management of disease and treatment-related complications. Baggott, C. R., Kelly, K. P., Fochtman, D. et al. Nursing Care of Children and Adolescents with Cancer. 3rd ed. Philadelphia, PA: W. B. Saunders Company; 2002: 11:279-319.

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