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LEUKOCYTOSIS

APPROACH TO THE PATIENT Leukocytosis

Review smear (? abnormal cells present) and obtain differential count. The normal values for concentration of blood leukocytes are shown in Table 69-1.

TABLE 69-1NORMAL VALUES FOR LEUKOCYTE CONCENTRATION IN BLOOD

INTRODUCTION

NEUTROPHILIA

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).

Causes

(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. 72); (9) metabolic (e.g., ketoacidosis, uremia); (10) other—malignant neoplasms, acute hemorrhage or hemolysis, after splenectomy.

LEUKEMOID REACTION

Extreme elevation of leukocyte count (>50,000/μL) composed of mature and/or immature neutrophils.

Causes

(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.

LEUKOERYTHROBLASTIC REACTION

Similar to leukemoid reaction with addition of nucleated red blood cells (RBCs) and schistocytes on blood smear.

Causes

(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).

LYMPHOCYTOSIS

Absolute lymphocyte count >5000/μL.

Causes

(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.

MONOCYTOSIS

Absolute monocyte count >800/μL.

Causes

(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 neutropenia; (5) malignant neoplasms...

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