II. Causes: Decreased Neutrophil Production
- Marrow Infiltration- Leukemia
- Myelodysplastic Syndrome
- Myelofibrosis (tumor invasion)
- Granulomatous infiltration (e.g. Tuberculosis)
 
- Marrow Injury- Radiation
- Aplastic Anemia
- Paroxysmal Nocturnal Hemoglobinuria
- Medications
- Infection
 
III. Causes: Increased Neutrophil Destruction
- Severe Sepsis (increased consumption)
- Antineutrophil Antibody
- Hypersplenism (Splenic trapping)
- Felty's Syndrome
- Systemic Lupus Erythematosus
- Chediak-Higashi Syndrome (rare Autosomal Recessive)
- Medications- Phenylbutazone
- Phenothiazine
 
IV. Causes: Lower Clinical Significance
- Pseudoneutropenia (based on automated count)
- Maturation Defect
- Margination (distribution)- Bacterial Infection (Endotoxin)
- Hemodialysis
- Cardiopulmonary bypass
 
