Patient Information Resource:
Benign Hematologic (Blood) DisordersA collaborative project of the Arizona Telemedicine Program, the Arizona Health Sciences Library and the Arizona Cancer Center.
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Leukocytosis
A. What Is Leukocytosis?
Leukocytosis is an increased number of leukocytes, or white blood cells (WBCs), in the blood. The WBCs are the blood cells responsible for the immune response, the fighting of infection. There are many different kinds of WBCs, each with their own particular function. WBCs are produced in the bone marrow, circulate for a time in the blood, and leave the blood to perform their function in the tissues. WBC levels may increase due to increased marrow production or decreased exit from the blood to the tissues.
B. Neutrophilia
Neutrophils are WBCs that move from the blood into the cells to kill invading bacteria and fungi. If neutrophil levels become too high, neutrophilia results. Neutrophilia is the most common form of leukocytosis. In a bacterial or fungal infection, more neutrophils are produced to fight the disease. However, there are many other causes of neutrophilia.
Among the causes of neutrophilia are infections (i.e. bacterial or fungal infections or tuberculosis), inflammatory diseases such as rheumatoid arthritis, and loss of blood cells through bleeding or hemolysis (destruction of blood cells). Elevations in hormones (such as adrenocorticosteroids and epinephrine) or steroid medications such as Prednisone may also increase neutrophil production. Other causes include cold, heat, exercise, seizures, pain, labor, surgery, panic, and rage. In addition, myeloproliferative disorders, causing proliferation of bone marrow cells, and cancer may also cause neutrophilia (for more on these, please see Myeloproliferative Disorders and Leukemia.
Symptoms of neutrophilia are usually the result of the underlying problem, such as signs of infection, bleeding, or bone marrow disorder. The disorder is diagnosed by patient history, physical examination for symptoms, and laboratory testing. The goal of diagnosis is to detect elevated neutrophil levels and to determine the cause of this problem. Treatment focuses upon addressing the underlying disorder or disease.
C. Eosinophilia and Basophilia
Eosinophils and basophils are WBCs involved in allergic reactions. When these cells increase in the body, eosinophilia and basophilia result. Common causes of eosinophilia include allergic reactions, skin disorders, parasitic infections, myeloproliferative disorders (leukemia, polycythemia vera, myelofibrosis), and other cancers. Basophilia is less common and is usually a symptom of myeloproliferative disorders or hyperthyroidism. The disorders are diagnosed by patient history, physical examination, and laboratory testing. Treatment attempts to address the underlying problem. For allergic reactions, antihistamines may be used to relieve allergic symptoms.
D. Monocytosis
Monocytes, like neutrophils, destroy bacteria and fungi in the cells. When monocyte levels in the blood become elevated, monocytosis results. Infections which may cause monocytosis include bacterial infections , protozoal infections such as malaria, rickettsial infections, and tuberculosis. In addition, diseases (such as ulcerative colitis, regional enteritis, sarcoidosis, and connective tissue disorders) and cancer (especially lymphomas and leukemias) may cause monocytosis. Diagnosis and treatment involve finding the underlying cause and, if possible, addressing it.
E. Lymphocytosis
The lymphocytes are a group of cells that fight viral and bacterial infections and other foreign material that may enter the body. Each type plays a specific role in immunity. In lymphocytosis, the level of lymphocytes in the blood increases. Lymphocytosis may result from most bacterial infections, infectious mononucleosis, or cancers such as leukemia or non-Hodgkin’s lymphoma. Symptoms include enlarged spleen and lymph nodes and the symptoms of the underlying infection or disease. Diagnosis and treatment involve patient history, physical examination, laboratory testing to identity cause, and treatment of underlying cause.
F. The Leukemoid Blood Picture
Leukemoid blood picture refers to an increased number of leukocytes, or white blood cells (WBCs). It is caused by increases in the number of precursor cells that will eventually grow into mature WBCs. This may occur in infections, bleeding from the digestive tract, cancer, or destruction of red blood cells in the blood (hemolysis; see Anemia). This is diagnosed based on patient history, physical examination, and laboratory examination for extensive bleeding and blood cell destruction.
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Updated: October 30, 2000