Low Blood Counts

 

A reduced number of blood cells in circulation is a common side effect of chemotherapy. Blood consists of three basic blood cell types: red blood cells, white blood cells, and platelets. Blood cells are produced in the bone marrow and are regularly released into the circulatory system.

Chemotherapy destroys cells that divide rapidly, a characteristic of cancer cells. However, bone marrow cells also divide rapidly and are frequently damaged by chemotherapy. The best way to treat low blood counts is to prevent them before they occur. This can be accomplished with the administration of blood cell growth factors. In some circumstances, blood transfusions may also be necessary. Blood counts are monitored with a laboratory test called a complete blood count (CBC).

What are the symptoms of low blood counts?

Your symptoms will depend on which types of blood cells are low. Common symptoms of the different types of low blood cell counts are listed below.

Common Symptoms of Low Blood Counts

Low Red Blood Cells

Low White Blood Cells

Low Platelets

Fatigue or tiredness

Infection

Excessive bruising

Trouble breathing

Fever

Excessive bleeding

Rapid heart rate

 

Nosebleeds

Difficulty staying warm

 

 

Pale skin

 

 

Dizziness

 

 

Lightheadedness

 

 

Why is it important to monitor blood counts?

It is important to monitor for low blood cell counts because this condition may:

  • Increase your risk of unpleasant and sometimes life-threatening side effects, such as fatigue, infection, and/or bleeding.
  • Disrupt delivery of your cancer treatment, resulting in a change to the planned dose and time.
  • Blood counts are monitored with a laboratory test called a complete blood count (CBC).

What are the treatments for low blood counts?

Low blood counts may be treated with blood cell growth factors, which were originally discovered as substances naturally produced by the body. These factors stimulate the cells in the bone marrow to produce more red blood cells, white blood cells, or platelets. Certain laboratory-produced blood cell growth factors are approved by the U.S. Food and Drug Administration (FDA) for the treatment of cancer patients with low blood counts.

Low red blood cell counts - Erythropoietin is a blood cell growth factor that selectively increases production of red blood cells. Clinical trials have demonstrated that erythropoietin is effective in increasing the number of red blood cells in cancer patients undergoing chemotherapy. It acts gradually, over a period of weeks.

When used as recommended, erythropoietin benefits patients by reducing the need for blood transfusions. A blood transfusion is the transfer of donated blood into a patient's bloodstream, through a vein. Blood transfusions raise blood cell counts quickly. However, they also carry important health risks, including infection, immune reactions, and inflammatory effects within blood vessels.

Erythropoietin is safe for most patients when used as recommended. It is also a powerful drug that may cause serious side effects in some patients, including abnormal blood clots, stroke, heart attack, death, and possible worse outcomes related to treatment of your cancer. Your physician should advise you of these risks and discuss any precautions that may apply to you. A low red blood count may also put you at risk, and there are potential risks in receiving a blood transfusion or in stopping chemotherapy to allow blood counts to rise. You and your physician must decide what option is most likely to help you with the least expected risk.

Erythropoietin is FDA-approved for the treatment of anemia (abnormally low red blood cell counts) in patients with nonmyeloid cancers (cancers that do not involve blood cells) whose anemia is a result of chemotherapy. For safety reasons, you should not receive erythropoietin for anemia if you are not receiving chemotherapy for a nonmyeloid cancer. Your physician should prescribe the lowest dose of erythropoietin that you need to keep your red blood cell count just high enough to avoid a blood transfusion. Be sure to ask what your hemoglobin count is.

Hemoglobin, the key oxygen-carrying protein in red blood cells, is measured through a standard laboratory test in units of grams per deciliter. Laboratory measurement of hemoglobin levels is one of the tests performed as part of the CBC.

Treatment with erythropoietin causes a gradual increase in red blood cell production. The body uses iron in red blood cell production. Thus supplemental iron may be required to adequately support erythropoietin-stimulated erythropoiesis (manufacturing of RBC’s). Many patients receiving erythropoietin therapy may eventually require supplemental iron therapy.

Currently, the commercially available forms of erythropoietin are Aranesp® (darbepoetin alfa), Epogen® (epoetin alfa), and Procrit® (epoetin alfa). Epoetin alfa is a form of erythropoietin that has been in use for many years. Darbepoetin alfa is a longer-acting form of erythropoietin that allows patients to receive fewer injections than with epoetin alfa.

The most common side effects seen in clinical trials with darbepoetin alfa in cancer patients receiving chemotherapy were fatigue, edema, nausea, vomiting, diarrhea, fever, and shortness of breath. Most of these side effects were from the chemotherapy or the anemia. No important differences in side effects were seen between groups treated with darbepoetin alfa and groups treated with the existing anemia treatment, epoetin alfa.

Low white blood cell count - The blood cell growth factors approved by the FDA for the prevention of chemotherapy-induced neutropenia (low neutrophils—one of the WBCs that fight infection) are Neupogen® (filgrastim) and Neulasta® (pegfilgrastim). Multiple clinical trials have shown that pegfilgrastim and filgrastim reduce the severity and duration of low white blood cell counts associated with many kinds of chemotherapy regimens.

By increasing white blood cell counts, filgrastim has been shown to decrease a patient's risk of fever and admission to the hospital. The drawback of filgrastim, however, is that it must be administered daily. In two clinical trials, a single dose of pegfilgrastim has been proven to be as effective as an average of 11 daily injections of filgrastim for the management of neutropenia. The most common side effect you may experience with pegfilgrastim is aching in the bones. If this happens, it can usually be relieved with a nonaspirin pain reliever, such as acetaminophen. It is also possible to have an allergic reaction to pegfilgrastim.

Low platelet count - The blood cell growth factor approved by the FDA for the prevention of low platelet count (thrombocytopenia) is called Neumega® (oprelvekin). Clinical studies have shown that oprelvekin prevents thrombocytopenia and decreases the need for platelet transfusions in patients at high risk for developing a low platelet count. Oprelvekin has been reported to cause palpitations, fluid retention, and diarrhea as well as other side effects in some patients.

Transfusions - In some cases, low blood counts may be so severe that you may need to undergo a blood transfusion. Red blood cells and platelets are often transfused. Transfusional blood can come from a blood bank, or you can store your own blood for future use before undergoing treatment. Transfusions may be associated with complications, including allergic reactions that may range from mild to life threatening. In general, it is better to prevent low blood counts than to treat them once they occur.

This content was last reviewed August 15, 2010 by Dr. Reshma L. Mahtani.
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