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The Merck Manual--Second Home Edition logo
 
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Chapter 174. White Blood Cell Disorders
Topics: Introduction | Neutropenia | Neutrophilic Leukocytosis | Lymphocytopenia | Lymphocytic Leukocytosis | Monocyte Disorders | Eosinophilic Disorders | Basophilic Disorders
 
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Lymphocytic Leukocytosis

Lymphocytic leukocytosis is an abnormally high number of lymphocytes in the blood.

The number of lymphocytes can increase in response to infections, especially by viruses. Some bacterial infections, such as tuberculosis, may also increase the number. Certain types of cancer, such as lymphoma and acute or chronic lymphocytic leukemia, may produce an increase in the number of lymphocytes, in part by releasing immature lymphocytes (lymphoblasts) or the lymphoma cells into the bloodstream. Graves' disease and Crohn's disease may also result in an increase in the number of lymphocytes in the bloodstream.

When the number of lymphocytes increases, symptoms usually result from the infection or other disease that has caused the number of lymphocytes to increase, rather than from the increase in lymphocytes per se. When a doctor discovers an increased number of lymphocytes, a blood sample is examined under a microscope to determine if the lymphocytes in the bloodstream appear activated (as occurs in response to viral infections) or if they appear immature or abnormal (as occurs in certain leukemias or lymphomas).

Treatment for lymphocytic leukocytosis depends on the cause.

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