<unk>  is an increase in the number or proportion of lymphocytes in the blood, usually detected when a complete blood count is routinely obtained. Lymphocytes are white blood cells that are derived from the common lymphoid progenitor, which arises from the hematopoietic stem cell. Lymphocytes include two broad categories: B cells and T cells. Both of these cell types arise from the bone marrow. B cells mature in the bone marrow, while T cells mature in the thymus. Lymphocytes normally represent 20 to 40% of circulating white blood cells. The absolute lymphocyte count can be directly measured by flow cytometry, or calculated by multiplying the total white blood cell count by the percentage of lymphocytes found in the differential count. For example, if the total WBC count is 30,000 per microliter, and the lymphocytes percentage is 10%, the absolute lymphocyte count is 3,000 per microliter. In absolute<unk> , the total lymphocyte count is elevated. In relative<unk> ,  there is a higher proportion of lymphocytes amongst the white blood cells compared to other subsets of white blood cells, but a normal absolute number of lymphocytes. In adults, absolute<unk>  is present when the absolute lymphocyte count is greater than 4,000 per microliter, while relative<unk>  is present if the absolute lymphocyte count is normal but the differential percentage of lymphocytes is higher than 40%. Relative<unk>  is normal in children under age 2.<unk>  can be a feature of infection, particularly in children. In the elderly, lymphoproliferative disorders, including chronic lymphocytic leukemia and lymphomas, often present with lymphadenopathy and a<unk> .
Lymphocytosis
Lymphocytopenia
Monocytosis
Leukocytosis
Neutrophilia
Plasmacytosis
Thrombocytopenia
Neutropenia