Harrisons Manual of Medicine, 18th Ed.

CHAPTER 69. Leukocytosis and Leukopenia

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 69-1 NORMAL VALUES FOR LEUKOCYTE CONCENTRATION IN BLOOD

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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 number 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, rick-ettsial 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.

EOSINOPHILIA

Absolute eosinophil count >500/μL.

Causes

(1) Drugs, (2) parasitic infections, (3) allergic diseases, (4) collagen vascular diseases, (5) malignant neoplasms, (6) hypereosinophilic syndromes.

BASOPHILIA

Absolute basophil count >100/μL.

Causes

(1) Allergic diseases, (2) myeloproliferative disorders (esp. CML), (3) chronic inflammatory disorders (rarely).

LEUKOPENIA

Total leukocyte count <4300/μL.

NEUTROPENIA

Absolute neutrophil count <2000/μL (increased risk of bacterial infection with count <1000/μL). The pathophysiology of neutropenia involves decreased production or increased peripheral destruction.

Causes

(1) Drugs—cancer chemotherapeutic agents are most common cause, also phenytoin, carbamazepine, indomethacin, chloramphenicol, penicillins, sulfonamides, cephalosporins, propylthiouracil, phenothiazines, captopril, methyldopa, procainamide, chlorpropamide, thiazides, cimetidine, allopurinol, colchicine, ethanol, penicillamine, and immunosuppressive agents; (2) infections—viral (e.g., influenza, hepatitis, infectious mononucleosis, HIV), bacterial (e.g., typhoid fever, miliary tuberculosis, fulminant sepsis), malaria; (3) nutritional—B12, folate deficiencies; (4) benign—benign ethnic neutropenia (BEN) seen in up to 25% of blacks, no associated risk of infection; (5) hematologic diseases—cyclic neutropenia (q21d, with recurrent infections common), leukemia, myelodysplasia (preleukemia), aplastic anemia, bone marrow infiltration (uncommon cause), Chédiak-Higashi syndrome; (6) hypersplenism—e.g., Felty’s syndrome, congestive splenomegaly, Gaucher’s disease; (7) autoimmune diseases—idiopathic, SLE, lymphoma (may see positive antineutrophil antibodies).

TREATMENT The Febrile, Neutropenic Patient

(See Chap. 26) In addition to usual sources of infection, consider paranasal sinuses, oral cavity (including teeth and gums), anorectal region; empirical therapy with broad-spectrum antibiotics (e.g., ceftazidime) is indicated after blood and other appropriate cultures are obtained. Prolonged febrile neutropenia (>7 days) leads to increased risk of dis seminated fungal infections; requires addition of antifungal chemotherapy (e.g., amphotericin B). The duration of chemotherapy-induced neutropenia may be shortened by a few days by treatment with the cytokines GM-CSF or G-CSF.

LYMPHOPENIA

Absolute lymphocyte count <1000/μL.

Causes

(1) Acute stressful illness—e.g., myocardial infarction, pneumonia, sepsis; (2) glucocorticoid therapy; (3) lymphoma (esp. Hodgkin’s disease); (4) immunodeficiency syndromes—ataxia telangiectasia and Wiskott-Aldrich and DiGeorge syndromes; (5) immunosuppressive therapy—e.g., antilymphocyte globulin, cyclophosphamide; (6) large-field radiation therapy (esp. for lymphoma); (7) intestinal lymphangiectasia (increased lymphocyte loss); (8) chronic illness—e.g., congestive heart failure, uremia, SLE, disseminated malignancies; (9) bone marrow failure/replacement—e.g., aplastic anemia, miliary tuberculosis.

MONOCYTOPENIA

Absolute monocyte count <100/μL.

Causes

(1) Acute stressful illness, (2) glucocorticoid therapy, (3) aplastic anemia, (4) leukemia (certain types, e.g., hairy cell leukemia), (5) chemotherapeutic and immunosuppressive agents.

EOSINOPENIA

Absolute eosinophil count <50/μL.

Causes

(1) Acute stressful illness, (2) glucocorticoid therapy.

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For a more detailed discussion, see Holland SM, Gallin JI: Disorders of Granulocytes and Monocytes, Chap. 60, p. 472; in HPIM-18.