| APPROACH TO THE PATIENT | ||
LeukocytosisReview smear (are abnormal cells present?) and obtain differential count. The normal values for concentration of blood leukocytes are shown in Table 64-1 Normal Values for Leukocyte Concentration in Blood. |
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. 66 Myeloid Leukemias, Myelodysplasia, and Myeloproliferative Syndromes); (9) metabolic (e.g., ketoacidosis, uremia); (10) other-malignant neoplasms, acute hemorrhage or hemolysis, after splenectomy, smoking, obesity.
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).
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.
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.
Absolute eosinophil count >500/µL.
Causes
(1) Drugs, (2) parasitic infections, (3) allergic diseases, (4) collagen vascular diseases, (5) malignant neoplasms, (6) hypereosinophilic syndromes.
Absolute basophil count >100/µL.
Causes
(1) Allergic diseases, (2) myeloproliferative disorders (esp. CML), (3) chronic inflammatory disorders (rarely).
Section 6. Hematology and Oncology