Extreme leukocytosis in the emergency department

Background: Extreme leukocytosis in the absence of haematological disease, is a topic about which little is known, although it may be associated with increased mortality among patients admitted to the intensive care department. The significance of extreme leukocytosis in patients presenting to hospital is uncertain. Aim: To study the correlates and prognostic significance of extreme leukocytosis, in patients admitted to an emergency department. Design: Observational study. Methods: Consecutive adult patients with extreme leukocytosis (>25 × 10⁹/l, n = 54) presenting to the emergency department of a university-affiliated hospital were compared to age-matched controls (±5 years) with moderate leukocytosis (12-25 ×10⁹/l, n = 118) presenting to the same department. Data were collected on demographic features, emergency room findings and hospital course. Results: Patients with extreme leukocytosis were more likely to suffer from infectious disease (74% vs. 48%, p < 0.01), to be hospitalized (100% vs. 80%, p < 0.001), and to die (32.1% vs. 12.7%, p < 0.01), and had a longer median length of stay (7.5 vs. 4.0 days, p< < 0.005). There was no significant difference in vital signs between the two groups. Discussion In our patients, extreme leukocytosis appeared to be predominantly caused by infectious disease, and was associated with a high case fatality rate. The degree of leukocytosis may provide prognostic information beyond that reflected in traditional vital signs.