TABLE OF CONTENTS
Many conditions cause abnormal WBC test results, including myelodysplastic syndromes, leukemia, and lymphoma. Myelodysplastic syndromes may affect as many as 10,000 Americans, but the exact number isn’t known, according to the American Cancer Society. Experts from the Leukemia & Lymphoma Society estimate that nearly 400,000 Americans are living with or in remission from leukemia, while approximately 875,000 people are living with or in remission from lymphoma.
This guide explains how the WBC test is used to diagnose and monitor medical conditions that can affect the number of white blood cells in the blood. It also provides in-depth information on myelodysplastic syndromes (MDS), leukemia, and lymphoma, including the symptoms of each condition and some of the most common treatment options.
The purpose of the WBC test is to measure the number of white blood cells in a person’s blood. A lower-than-normal number of WBCs is a sign of many serious medical conditions, including bone marrow failure, autoimmune disorders, severe bacterial infections, and an infection called mononucleosis. Too many WBCs can also indicate a serious problem. Some of the conditions that can cause high a high WBC count include leukemia, rheumatoid arthritis, serious infections, and tissue damage. Having the WBC test can help diagnose one of these conditions, or another condition, in a timely manner. WBC testing is also used to monitor individuals who are taking medications that can raise or lower their WBC counts.
According to MedlinePlus, the WBC test should be ordered when an individual has signs of inflammation, blood cancers, serious infections, or allergic reactions. Regular testing may also be necessary for people who take certain medications. For example, antibiotics, certain medications used to lower blood pressure, and diuretics can all lower a person’s WBC count. Heparin (a blood thinner), corticosteroids, and some medications used to treat asthma can cause an individual’s WBC count to increase.
The WBC test requires a blood sample.
In many cases, no special preparation is required for the WBC test; however, some medications can affect the results. It may be necessary to stop taking these medications a few days before the test.
The term myelodysplastic syndromes (MDS) refers to several cancers that prevent immature blood cells from maturing normally. Immature blood cells begin as stem cells and divide into immature WBCs, immature platelets, or immature red blood cells (RBCs). These immature cells are supposed to continue dividing until they have matured. In people with MDS, this process is interrupted, which prevents the immature cells from turning into mature WBCs, platelets, or RBCs.
WBCs can be involved in two types of MDS. People with refractory cytopenia with multilineage dysplasia don’t have enough of at least two of the three types of blood cells. For example, someone with refractory cytopenia with multilineage dysplasia may have too few WBCs and too few RBCs. People with refractory cytopenia with unilineage dysplasia have too few of one type of blood cell and changes in 10% or more of the other two cell types. For example, someone with refractory cytopenia with unilineage dysplasia may have too few WBCs and changes in 10% or more of their RBCs and platelets.
Having one of these forms of MDS can cause frequent infections, and, when an infection develops, it may also be more severe than usual. Other signs and symptoms of MDS involving too few WBCs include fever, loss of appetite, unexplained weight loss, and bone pain.
Leukemia develops due to changes in a single cell of the bone marrow. The abnormal cell, known as a leukemia cell, may grow faster than healthy cells, resulting in an overgrowth of leukemia cells and a lack of normal cells. Acute lymphoblastic leukemia, acute myeloid leukemia, chronic lymphoblastic leukemia, and chronic myeloid leukemia are some of the most common types of leukemia.
Some people have a greater risk of developing leukemia than others. For example, exposure to solvents or high levels of radiation can increase the risk. Other risk factors for leukemia include smoking, having a history of myelodysplastic syndromes or rare genetic syndromes, a family history of the disease, or a history of having radiation treatment or chemotherapy to treat other types of cancer. However, just because someone has a risk factor doesn’t mean he or she will definitely develop leukemia.
The signs and symptoms of leukemia include pale skin, fatigue, fever, frequent nosebleeds, swollen lymph nodes, unintended weight loss, joint pain, and night sweats. Some people with leukemia also have shortness of breath, bleeding gums, and abdominal pain on the left side.
Lymphoma is a type of cancer that affects the lymphatic system, which consists of several tissues and organs that carry lymph fluid throughout the body. This fluid transports white blood cells, making it essential for normal immune function. Lymphoma can be classified as either Hodgkin lymphoma (Hodgkin disease) or non-Hodgkin lymphoma. Hodgkin disease is a rare form of lymphoma caused by changes in a type of white blood cell known as a B lymphocyte. These changes affect the growth and division of the cells, causing symptoms such as fever, night sweats, chills, weight loss, itching, loss of appetite, and swelling of the lymph nodes.
Non-Hodgkin lymphomas are caused by abnormalities in B cells or T cells, which are both types of leukocytes. The abnormal cells divide rapidly and spread to other parts of the body, crowding out healthy cells. People with certain infections and weakened immune systems have a higher risk of developing this disease. Symptoms of non-Hodgkin lymphoma include chest pain, coughing, difficulty breathing, swollen lymph nodes, abdominal pain, abdominal swelling, and persistent fatigue.
Several methods are used to count the number of WBCs in a person’s blood. Many laboratories use automated counters, while others do manual counting with special chambers. In some cases, the ordering physician requests a differential, which determines the percentage of each of the five main types of WBCs in the blood. The five main types of white blood cells are monocytes, lymphocytes, eosinophils, basophils, and neutrophils.
Monocytes play an important role in breaking down bacterial organisms. Lymphocytes are responsible for producing antibodies, which are proteins that can fight off bacteria, viruses, and other harmful organisms. Eosinophils are involved in allergic responses; they also kill cancer cells and parasites. Basophils release histamine, a substance involved in the inflammatory response. Neutrophils destroy fungi and bacteria.
According to the National Cancer Institute, three main types of treatment are used to help people with MDS: supportive therapies, medications, and chemotherapy/stem cell transplant. Supportive care does not cure MDS, but it eases the symptoms and may improve the quality of the individual’s life. In some cases, blood transfusions are given to replace the WBCs that have been destroyed by MDS or other treatments. Antibiotics may also be given to people with MDS who develop severe infections.
Several medications can be used to treat MDS, including decitabine and azacitidine, lenalidomide, chemotherapy, and immunosuppressive therapy. Decitabine and azacitidine are used to kill abnormal cells and prevent MDS from turning into acute myeloid leukemia. Lenalidomide reduces the need for transfusions of red blood cells. Immunosuppressive drugs make the immune system less active, which can also reduce the need for RBC transfusions. Some people with MDS have an increased risk of developing acute leukemia; these people may benefit from taking the same chemotherapy drugs that are used to treat acute myeloid leukemia.
In some cases, people with MDS take chemotherapy to kill the cancer cells. Before starting the chemotherapy regimen, an individual has stem cells harvested from their bone marrow. These cells are kept in frozen storage. Once the individual finishes chemotherapy, the healthy stem cells are transplanted back into the bone marrow; they eventually mature into white blood cells, red blood cells, and platelets.
Chemotherapy, stem cell transplant, targeted therapy, immunotherapy, and radiation therapy are the main treatments for leukemia. The right treatment depends on several factors, including the individual’s age and health status. Chemotherapy kills the leukemia cells so they can’t keep dividing uncontrollably. Stem cell transplantation replaces the leukemia cells with healthy stem cells. Targeted therapies can help people with leukemia in several ways. Some drugs prevent the leukemia cells from dividing, while others destroy the cells. Targeted therapies can also be used to cut off the blood supply to the leukemia cells. Because the therapy is targeted to the cancerous cells, fewer healthy cells die, which can prevent complications during treatment. Immunotherapy boosts the immune system, making it better able to fight leukemia. Radiation therapy prevents leukemia cells from growing. This treatment involves directing radiation at clusters of cancerous cells.
The five main treatments for leukemia are also standard treatments for non-Hodgkin lymphoma. People with non-Hodgkin lymphoma may also benefit from plasmapheresis, surgery, or antibiotic therapy. Plasmapheresis can relieve circulation problems caused by having too many antibody proteins in the blood. During this process, the individual’s blood is sent through a machine that separates the blood cells from the plasma. The blood cells are returned to the patient’s body, but the excess antibodies are discarded.
Surgery is sometimes used to help people with particularly aggressive forms of non-Hodgkin lymphoma. In an individual with lymphoma of the spleen, it may be necessary for a surgeon to perform a splenectomy, which involves removing the spleen from the body. Surgery may also be used to treat people with lymphoma in the small intestine. Antibiotics are used to kill bacteria that can cause cancer and severe infections. Chemotherapy, targeted therapy, radiation therapy, and immunotherapy are the standard treatments for Hodgkin disease.
A normal WBC count ranges from 4,500 to 11,000 WBCs per microliter of blood.
Basophils: 0.5% to 1%
Eosinophils: 1% to 4%
Lymphocytes: 20% to 40%
Monocytes: 2% to 8%
Neutrophils: 40% to 60%
Taking certain medications, smoking cigarettes, and having a splenectomy (spleen removal) can all result in an elevated WBC level. A high WBC count can also be caused by burns and other forms of tissue trauma.
A low WBC count can be caused by lupus, liver diseases, viruses, severe physical distress, high levels of emotional stress, and diseases that affect the spleen.
If an individual’s WBC count is slightly higher than normal or slightly lower than normal, the ordering physician may decide to repeat the test at a later date; however, if the individual has worrisome symptoms, such as unexplained fevers or weakness, a health care provider may order additional blood tests, X-rays, or imaging tests to determine the underlying cause.
In some cases, a bone marrow biopsy is necessary to determine if the cells in the bone marrow are normal or abnormal. This type of biopsy can be used to determine if there are too many immature cells in the marrow, or it can be used to identify leukemia cells among the healthy cells in the bone marrow. During this procedure, a doctor inserts a needle into one of the large bones — usually the hip bone — and draws out liquid containing bone marrow cells. The doctor also takes a sample of the solid bone marrow. These samples are analyzed by a pathologist to determine if there are any cell abnormalities or other issues that could indicate that a patient has MDS, leukemia, lymphoma, or another disease.
For more information on MDS, leukemia, and lymphoma, along with testing for these conditions, visit the following online resources.
|Bone Marrow & Cancer Foundation||www.bonemarrow.org||The BMCF aims to support people with diseases that can affect the bone marrow.|
|American Cancer Society||www.cancer.org||Learn more about cancers that can affect an individual’s WBC count.|
|Aplastic Anemia and MDS International Foundation||www.aamds.org||Find information about aplastic anemia and other conditions that can cause a low WBC.|
|MedlinePlus||www.medlineplus.gov||Access articles and other resources on lab testing for MDS, leukemia, and lymphoma.|
|National Center for Biotechnology Information||www.ncbi.nlm.nih.gov/books||Search for information on medical conditions that can affect the results of the WBC test.|