Numerous drugs have been associated with neutropenia. The highest-risk categories are antithyroid medications, macrolides, and procainamides. Many drugs act by an immune-mediated mechanism. However, some drugs appear to have direct toxic effects on marrow stem cells or neutrophil precursors in the mitotic compartment. For example, drugs such as the antipsychotics and antidepressants and chloramphenicol may act as direct toxins in some individuals, based on metabolism and sensitivity in this manner. Other drugs may have a combination of immune and nonimmune mechanisms or may have unknown mechanisms of action.
Cyclic neutropenia is characterized by periodic bouts of neutropenia associated with infection, followed by peripheral neutrophil count recovery. Its periodicity is about 21 days (range, 12-35 days). People with cyclic neutropenia typically present as infants or children, but acquired forms in adulthood are noted. The prognosis is good, with a benign course; however, 10% of patients will experience life-threatening infections.
Shwachman syndrome has an autosomal recessive inheritance pattern. The neutropenia is moderate to severe, with a mortality rate of 15%-25%, and the syndrome presents in infancy, with recurrent infections, diarrhea, and difficulty in feeding. Dwarfism, chondrodysplasia, and pancreatic exocrine insufficiency can occur.
Infections are the most common form of acquired neutropenia. Viral infections often lead to mild or moderate neutropenia. Agranulocytosis is uncommon but may occur. The most commonly involved organisms are from endogenous flora. Staphylococcus aureus organisms are found in cases of skin infections. Gram-negative organisms are observed in infections of the urinary and gastrointestinal tracts, particularly Escherichia coli and Pseudomonas species. Candida albicans infections may also occur. Mixed flora may be found in the oral cavity.
For more on the etiology of neutropenia, read here.
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Cite this: Elwyn C. Cabebe. Fast Five Quiz: How Much Do You Know About Neutropenia? - Medscape - Nov 22, 2017.