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Full Blood Count


February 15th, 2021


Lymphocytes are small leukocytes with a large nucleus, though they may be larger with a low nuclear : cytoplasmic ratio if they are reactive.
    • Normal Range

    • 1.0 - 4.0 x 10⁹/L
    • 20 - 40% of total leukocytes


Lymphocytosis refers to an increase in the number of circulating lymphocytes.
  • Causes of Lymphocytosis

  • Acute viral infection - EBV, CMV, viral hepatitis, influenza
  • Chronic infection - TB, brucellosis, pertussis
  • Lymphoproliferative disorders - chronic lymphocytic leukaemia, lymphoma
  • Hyposplenism - splenectomy, liver cirrhosis, coeliac disease, sickle cell disease, SLE
  • Endocrine pathology - thyrotoxicosis, adrenocortical insufficiency
  • Autoimmune disease


Lymphopaenia refers to a reduction in the number of circulating lymphocytes.
  • Causes of Lymphopaenia

  • Inherited
  • Primary immunodeficiency disorders - e.g. severe combined immunodeficiency, Wiskott-Aldrich syndrome
  • Acquired
  • Acute stress - infection, trauma, burns, surgery
  • Drugs - corticosteroids, cytotoxic chemotherapy, methotrexate, azathioprine, rituximab, clozapine
  • HIV infection / AIDS
  • Autoimmune disease (especially SLE)
  • Cushing's syndrome
  • Hodgkin lymphoma
  • Aplastic anaemia
  • Alcohol abuse
  • Sarcoidosis
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