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Hyperleukocytosis is a life-threatening oncology emergency, defined as a white blood cell (WBC) count ≥ 100,000/µL and can occur in up to 20% of patients with acute myeloid or lymphoid leukemias (Abla et al., 2016). Hyperleukocytosis may lead to leukostasis and subsequent end organ damage, commonly affecting the central nervous system, respiratory and renal systems, and can also cause tumor lysis syndrome (TLS), another oncology emergency, and lead to metabolic derangements and further renal dysfunction (Porcu et al., 2000). Treatment of hyperleukocytosis includes supportive care, early initiation of chemotherapy and/or leukapheresis (Zhang et al., 2021). There are no definitive guidelines on the use or efficacy of leukapheresis in hyperleukocytosis. Within published literature there is a lack of consistency in decision to treat and selection biases (as physician discretion was used as an indication for leukapheresis), variability in treatment (whether or not to administer chemotherapy), and differences in outcome measures (Zhang et al., 2021). According to the American Society of Apheresis Guidelines, the indication for use of leukapheresis as treatment for hyperleukocytosis falls under category III, meaning the quality of published evidence has not established the optimum role of leukapheresis and thus decision making should be based on individual cases (Connelly‐Smith et al., 2023). Development of a clinical pathway for hyperleukocytosis and leukapheresis will allow for standardized management strategies for patients at Children’s Mercy Kansas City (CMKC)

Publication Date



These guidelines do not establish a standard of care to be followed in every case. It is recognized that each case is different and those individuals involved in providing health care are expected to use their judgment in determining what is in the best interests of the patient based on the circumstances existing at the time. It is impossible to anticipate all possible situations that may exist and to prepare guidelines for each. Accordingly, these guidelines should guide care with the understanding that departures from them may be required at times.

Objective of the Clinical Pathway

To provide care standards for the patient diagnosed with acute leukemia experiencing hyperleukocytosis. This clinical pathway provides guidance regarding determination of the need for leukapheresis, and once the need has been established, the process to ensure timely communication and initiation of leukapheresis

Target Users

Physicians (Hematology/Oncology, Critical Care, Transfusion Medicine, Apheresis Program); Advance Practice Providers; Nurses




Finalized Nov 2023

Clinical Practice Guidelines are updated on a revision schedule. Primary files will always be the most current update. Previous revisions are available upon request from Children’s Mercy Library Services.

Clinical Pathways promote evidence based, safe, and high-value care for patients with common or high-risk clinical conditions when national or international guidelines are not available or applicable. Clinical Pathways are informed by methodical review of scientific literature and the consensus of a multidisciplinary committee of subject matter experts and key stakeholders at Children’s Mercy Kansas City. Processes within Clinical Pathways may be specific to Children’s Mercy Kansas City and should be evaluated before applying to a different setting.


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