Hyperleukocytosis is often seen in acute presentations childhood leukemias, and is defined as a WBC count of greater than 30-50K.  Complications usually arise at counts greater than 300, however, keep in mind that automated cell counters may underestimate very high white counts.

Complications include:

• Hyperviscosity Syndrome / Leukostasis
  • Risk of CVA, PE, Mesenteric Ischemia, etc.
• Tumor Lysis Syndrome (TLS)
  • Risk of fatal arrhythmia, may monitor with K, LDH, Uric Acid
• Disseminated Intravascular Coagultion (DIC)

Treatment:

• EMERGENT LEUKOREDUCTION APHERESIS, aka Leukopheresis
• This is a true emergency - if you are at a facility without leukopheresis capability, the fastest transport mode possible is indicated - fly, don't drive
• Temporizing measures include fluids, fluids, and fluids
• Allopurinol / Rasburicase may be considered, but not if this will delay transport, especially if there is no evidence of TLS - this decision may be made in consultation with the pediatric heme/onc specialist who is helping to arrange for leukopheresis