hyperleukocytosis
Pronunciation: hy-per-loo-ko-sy-TOH-sis
Extremely elevated white blood cell count, typically above 100,000/μL, constituting a medical emergency.
Full Definition
Hyperleukocytosis is defined as a white blood cell count exceeding 100,000 cells per microliter, though some sources use 50,000/μL as the threshold. This condition represents a hematologic emergency due to the risk of leukostasis, where excessive circulating blasts cause microvascular occlusion in vital organs, particularly the lungs and brain. Complications include respiratory distress, altered mental status, and disseminated intravascular coagulation. Immediate management includes leukapheresis, aggressive hydration, and rapid initiation of cytoreductive therapy. Hyperleukocytosis is most commonly encountered in acute leukemias but can occur in chronic hematologic malignancies during blast crisis.
Usage
Usage note: Single word, not hyphenated; distinguish from general leukocytosis
In Context
- "The patient presented with hyperleukocytosis and signs of leukostasis requiring emergent leukapheresis." — Emergency department case presentation
- "Hyperleukocytosis at diagnosis was associated with increased early mortality in the pediatric cohort." — Clinical research analysis