Total leukocyte count <4300/µL.
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) genetic-benign ethnic neutropenia (BEN) seen in up to 25% of blacks, no associated risk of infection; inheritance of an allele of the Duffy antigen receptor for cytokines (DARC rs2814778) can be associated with constitutive neutropenia that is not associated with predilection to infection; more common in African Americans; (5) hematologic diseases-cyclic neutropenia (q21d, with recurrent infections common), leukemia, myelodysplasia (preleukemia), aplastic anemia, bone marrow infiltration (uncommon cause), Chédiak-Higashi syndrome; treatment with G-CSF is safe and effective over many years; (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 PtSee Chap. 82 Infections in the Immunocompromised Host. 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 or cefapime) is indicated after blood and other appropriate cultures are obtained. Prolonged febrile neutropenia (>7 days) leads to increased risk of disseminated fungal infections; requires addition of antifungal chemotherapy (e.g., amphotericin B, liposomal amphotericin B, voriconizole). The duration of chemotherapy-induced neutropenia may be shortened by a few days by treatment with the cytokines G-CSF. |
Absolute lymphocyte count <1000/µL.
Causes
(1) Acute stressful illness-e.g., myocardial infarction, pneumonia, sepsis; (2) glucocorticoid therapy; (3) lymphoma (esp. Hodgkin's lymphoma); (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.
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.