(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); (8) genetics—inheritance of an allele of the Duffy antigen receptor for cytokines (DARC) can be associated with constitutive neutropenia that is not associated with predilection to infection; more common in African Americans.
Treatment: Thrombotic Disorders 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 disseminated 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. |
Section 6. Hematology and Oncology