Synopsis
Interpret raised white-cell counts by lineage, time course and morphology, recognise reactive physiological and infective patterns, and escalate blasts, clonal lymphocytosis or unexplained persistence appropriately.
- Leucocytosis is a laboratory description; classify the absolute neutrophil, lymphocyte, monocyte, eosinophil and basophil counts rather than interpreting the total alone.
- Neutrophilia commonly accompanies bacterial infection, inflammation, tissue necrosis, corticosteroids, smoking, pregnancy, G-CSF, stress and splenectomy.
- Reactive lymphocytosis is common in viral infection and can show large activated lymphocytes; pertussis and some bacterial or parasitic infections also raise lymphocytes.
Key red flags
New hypoxia, confusion, focal neurology or retinal disturbance with suspected acute leukaemia requires emergency cytoreduction planning.
Investigation priorities
Confirm lineage, persistence and associated cytopenias.
Management branches
A raised white-cell count is accompanied by systemic or haematological symptoms.
- Assess breathing, neurology, retina, bleeding, infection and spleen and review haemoglobin, platelets, film flags, coagulation and tumour-lysis markers.
- Call haematology immediately for blasts, promyelocyte concern, leukostasis physiology, major cytopenias or tumour lysis and avoid delaying definitive sampling.
Key medicines
No medicine for an uncomplicated reactive countDo not prescribe cytoreduction or antimicrobial treatment solely for the white-cell number; treat a clinically defined infection, inflammation or exposure using its own regimen.
Emergency cytoreductionA haematologist selects hydroxycarbamide, leukapheresis or disease-specific induction according to leukaemia subtype, symptoms, count kinetics and tumour-lysis risk.