Absolute lymphocyte count, also known as lymphocyte count, has a normal reference value: adults (0.8-4) × 10*9/L. Lymphocyte count is affected by both physiological and pathological factors; therefore, low absolute peripheral blood lymphocyte count is commonly due to the following causes: Certain drugs can cause lymphocytopenia, such as menadione, nitrogen mustard phenylbutyrate, cortisone, epinephrine, lithium, nixic acid, steroids, etc. Secondly, immune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, mixed connective tissue disease, polymyositis, decrease in lymphocytes due to antibody production of anti-lymphocyte antibodies, resulting in destruction of lymphocytes, and the degree of reduction is related to the titer of the antibody; recovery from influenza; radiation therapy can destroy lymphocytes, with each low-dose radiation therapy producing more destruction than 2 high-dose radiation therapy per week; alkyl treatment with alkylating agents (cyclophosphamide, etc.) can cause a marked decrease in white blood cells with a marked decrease in lymphocytes, which can persist for several years after cessation of treatment; early lymphocytopenia in tuberculosis, with a marked decrease in CD4+ cells, which can return to normal if treatment is effective; various types of congenital immunodeficiency such as severe combined immunodeficiency, ataxia capillaris malnutrition, or zinc deficiency, can cause varying degrees of lymphocytopenia.
The diagnosis of the disease cannot be made on the basis of low absolute lymphocyte values alone, because the causes of low absolute lymphocyte values are diverse and need to be combined with other clinical symptoms and relevant laboratory tests to clarify the cause and diagnose the disease.