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APPROACH TO THE PATIENT: Leukocytosis
Review smear (are abnormal cells present?) and obtain differential count. The normal values for concentration of blood leukocytes are shown in Table 63-1.
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Absolute neutrophil count (polys and bands) >10,000/μL. The pathophysiology of neutrophilia involves increased production, increased marrow mobilization, or decreased margination (adherence to vessel walls).
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(1) Exercise, stress; (2) infections—esp. bacterial; smear shows increased numbers of immature neutrophils (“left shift”), toxic granulations, Döhle bodies; (3) burns; (4) tissue necrosis (e.g., myocardial, pulmonary, renal infarction); (5) chronic inflammatory disorders (e.g., gout, vasculitis); (6) drugs (e.g., glucocorticoids, epinephrine, lithium); (7) cytokines [e.g., granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF)]; (8) myeloproliferative disorders (Chap. 65); (9) metabolic (e.g., ketoacidosis, uremia); (10) other—malignant neoplasms, acute hemorrhage or hemolysis, after splenectomy.
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Extreme elevation of leukocyte count (>50,000/μL) composed of mature and/or immature neutrophils.
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(1) Infection (severe, chronic, e.g., tuberculosis), esp. in children; (2) hemolysis (severe); (3) malignant neoplasms (esp. carcinoma of the breast, lung, kidney); (4) cytokines (e.g., G-CSF, GM-CSF). May be distinguished from chronic myeloid leukemia (CML) by measurement of the leukocyte alkaline phosphatase (LAP) level: elevated in leukemoid reactions, depressed in CML.
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LEUKOERYTHROBLASTIC REACTION
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Similar to leukemoid reaction with addition of nucleated red blood cells (RBCs) and schistocytes on blood smear.
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(1) Myelophthisis—invasion of the bone marrow by tumor, fibrosis, granulomatous processes; smear shows “teardrop” RBCs; (2) myelofibrosis—same pathophysiology as myelophthisis, but the fibrosis is a primary marrow disorder; (3) hemorrhage or hemolysis (rarely, in severe cases).
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Absolute lymphocyte count >5000/μL.
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(1) Infection—infectious mononucleosis, hepatitis, cytomegalovirus, rubella, pertussis, tuberculosis, brucellosis, syphilis; (2) endocrine disorders—thyrotoxicosis, adrenal insufficiency; (3) neoplasms—chronic lymphocytic leukemia (CLL), most common cause of lymphocyte count >10,000/μL.
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Absolute monocyte count >800/μL.
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(1) Infection—subacute bacterial endocarditis, tuberculosis, brucellosis, rickettsial diseases (e.g., Rocky Mountain spotted fever), malaria, leishmaniasis; (2) granulomatous diseases—sarcoidosis, Crohn’s disease; (3) collagen vascular diseases—rheumatoid arthritis, systemic lupus erythematosus (SLE), polyarteritis nodosa, polymyositis, temporal arteritis; (4) hematologic diseases—leukemias, lymphoma, myeloproliferative and myelodysplastic syndromes, hemolytic anemia, chronic idiopathic ...