Clinical Outcomes of Extreme Leukocytosis in ICU Patients: An Insight into Mortality and Supportive Care Needs
Authors: Sood Aditya , Sangari Anish , Locke Margaret , Elengickal Joseph , Wright Jervon , Hou Lilly , Aung Wint Yan , George Riya , Singhal Adit , Nieto Maria J 
Published: December 2024

Introduction
Extreme leukocytosis, characterized by a high white blood cell (WBC) count exceeding 100,000/microliter, poses exceptional clinical challenges in the intensive care unit (ICU). Though rare, extreme leukocytosis is strongly linked with increased morbidity and mortality. As such, it necessitates swift and accurate diagnostic and therapeutic interventions. This study seeks to uncover the short-term outcomes and immediate care necessities of extreme leukocytosis, providing essential insights for acute care management strategies.
Methods:
This retrospective study analyzed data from the TriNetX federated research network, which includes electronic medical records from 115 healthcare organizations worldwide, including academic medical centers and community hospitals. The network's database, updated as of March 2024, encompasses records of 143 million patients, providing detailed information on diagnoses, procedures, medications, laboratory values, and partially genomic data.
We identified 993 patients with extreme leukocytosis, defined as a white blood cell count exceeding 100,000/microliter, who were admitted to the ICU within ten days before or after this finding. The primary objective was to assess one-month outcomes including mortality, respiratory support via ventilation, renal support through hemodialysis or continuous renal replacement therapy (CRRT), and the need for vasopressor support.
Results
Our study evaluated a cohort of 993 ICU patients diagnosed with extreme leukocytosis within ten days of admission. Among these, one-month mortality data available for 978 patients indicated a mortality rate of 9.71%, highlighting a significant acute mortality risk linked with this condition. The demands for critical care support varied across systems. 12.99% of patients required vasopressor support due to cardiovascular instability. Renal complications were also prevalent, with 6.14% of patients requiring interventions such as hemodialysis or CRRT. Mechanical ventilation was required for 3.12% of patients, reflecting severe respiratory challenges.
Discussion
This study identifies significant interdependencies between extreme leukocytosis and critical care requirements, including high rates of cardiovascular instability and renal impairment, resulting in substantial needs for vasopressor and renal support. The mortality rate within one month of ICU admission, although lower than anticipated, still underscores this condition's grave nature. The high correlation between extreme leukocytosis and the need for intensive care interventions suggests potential underlying etiologies, notably acute hematologic malignancies, which might not only be driving the WBC elevation but also be contributing to the overall poor prognosis. These findings underscore the importance of devising focused diagnostic pathways and tailored management strategies for this patient population. Further studies should aim to delineate more precisely the relationship between specific types of hematologic malignancies and extreme leukocytosis, potentially leading to more targeted therapies that could enhance patient outcomes. The limitations of this study include its retrospective nature and the potential for selection bias inherent in the use of a federated database; prospective studies are needed to validate and expand upon these findings.