Leukaemoid reaction

Last updated: Friday, 17, December, 2010
CausesAppropriate Tests

Extreme leucocytosis (usually >50x 109/L), often with immature white cells, and a superficial resemblance to leukaemia.

Review clinical features, FBC, blood film, differential WCC; consult pathologist.

See also Table 4 Reference intervals for leucocyte differential counts, Neutrophilia, Neutrophilia, with early myeloid cells (blood film)

Myeloid reaction

Carcinoma, especially

  • Advanced and/or metastatic

Severe/chronic bacterial infection, especially

Cytokine therapy, especially

  • G-CSF

Recovery from bone marrow aplasia

Lymphoid reaction


Infectious mononucleosis