Leukocytosis

Type

Clinical features

Definitions

•  Leukocytosis 

• •  WBC > 11,000 cells/microliter 
  •  Can include neutrophils, basophils, eosinophils, monocytes, lymphocytes
•  Neutrophils 

• •  Make up 40-70% of white blood cells (WBC)
  •  Mature neutrophils also known as polymorphonuclear cells (PMNs)
•  Absolute neutrophil count (ANC)
  •  Number of neutrophils + bands
  •  Excludes metamyelocytes and less mature forms
  •  ANC= WBC (cells/microliter) times percent (bands + PMNs)
•  Neutrophilia
  •  ANC > 7700 cells/microliter
•  Left shift
  •  Increased percentage of bands usually with metamyelocytes  and myelocytes
•  Leukemoid reaction
  •  WBC > 50,000 cells/microliter
•  Absolute lymphocyte  count (ALC)

• •  ALC= (WBC times percent lymphocytes)/100
•  Lymphocytosis
  •  ALC > 4000 cells/microliter
•  Absolute eosinophil count (AEC)
  •  Number of eosinophils in peripheral blood
  •  AEC= (WBC count/microliter) ( percentage of eosinophils)
•  Eosinophilia
  •  AEC > 500 eosinophils/microliter
•  Hypereosinophilia
  •  AEC > 1500 eosinophils/microliter with or without end organ damage
•  Hypereosinophilic syndrome (HES)
  •  Hypereosinophilia on 2 occasions > 1 month apart with organ dysfunction

Mechanisms of leukocytosis

•  Increased bone marrow production or differentiation of precursor cells
•  Decreased destruction of cells
•  Redistribution of ciculating cells to blood from bone marrow or secondary lymphoid organs