Synopsis
Recognise cellular and paraprotein-mediated microcirculatory emergencies, distinguish their mechanisms, reduce viscosity safely and coordinate immediate definitive treatment of the underlying clone.
- Hyperleukocytosis is a numerical finding, commonly leukocytes above 100 × 10⁹/L; leukostasis is clinical organ dysfunction and can occur at lower AML counts.
- Key leukostasis organs are lung and brain: dyspnoea, hypoxia, confusion, headache, focal deficit, seizure and retinal change with blast-rich disease require emergency cytoreduction.
- First-line tests are urgent FBC and film, coagulation and fibrinogen, renal, calcium, phosphate, potassium, urate, LDH, cultures, group sample and leukaemia flow and molecular samples.
Key red flags
Hypoxia, tachypnoea or bilateral pulmonary infiltrates with marked myeloid leukocytosis may be leukostasis and can worsen during early cell lysis.
Tachypnoea, hypoxia, diffuse infiltrates and respiratory failure with blast-rich hyperleukocytosis can mimic infection or oedema and demand parallel treatment.
Investigation priorities
Identify cell burden, lineage clues, anaemia, thrombocytopenia and an APL-like morphology.
Management branches
Acute pulmonary, neurological, retinal or priapic dysfunction occurs with blast-rich hyperleukocytosis.
- Call acute leukaemia, critical care and apheresis teams and obtain clonal, lysis, coagulation, culture and group samples.
- Start monitored hydration and tumour-lysis prophylaxis and use immediate definitive therapy or hydroxycarbamide bridging.
Key medicines
Hydroxycarbamide for emergency cytoreductionGive 50 to 100 mg/kg/day orally in 2 or 3 divided doses under the acute-leukaemia protocol, with a maximum and dose adjustment defined by renal function and response, until definitive therapy controls the count.
Therapeutic plasma exchangeExchange approximately 1 to 1.5 calculated plasma volumes with the apheresis replacement protocol urgently, repeating according to symptoms, fundal findings, immunoglobulin and viscosity rebound.