From the Guidelines
Yes, a stroke can produce leukocytosis, an elevated white blood cell count, as a result of the body's inflammatory response to brain tissue damage. This increase in WBCs typically occurs within hours after stroke onset and may persist for several days 1. The leukocytosis is primarily due to the release of damage-associated molecular patterns (DAMPs) that trigger an immune response, leading to the mobilization of white blood cells from bone marrow reserves.
Key Points to Consider
- The degree of leukocytosis often correlates with stroke severity and infarct size, with counts typically ranging from 10,000-20,000 cells/μL, though they can be higher 1.
- This post-stroke leukocytosis is considered a stress response and part of the body's natural healing process, though excessive inflammation may contribute to secondary brain injury.
- Clinicians should be aware that while leukocytosis is common after stroke, persistent or extreme elevations may warrant investigation for concurrent infection or other complications 1.
- Factors such as history of hypertension, history of heart failure, and presence of elevated white blood cell count can increase the development of fatal brain edema 1.
Clinical Implications
- Monitoring of white blood cell count is essential in the management of stroke patients to identify potential complications early.
- The presence of leukocytosis should prompt clinicians to investigate for underlying causes, such as infection, and to manage accordingly.
- Management strategies should focus on preventing further deterioration from tissue displacement and brain stem shift, and correcting factors that could exacerbate swelling, such as hypoxemia, hypercarbia, and hyperthermia 1.
From the Research
Leukocytosis in Stroke
- Leukocytosis, an increase in White Blood Cell (WBC) count, is a common finding in the acute phase of stroke 2.
- Studies have shown that leukocytosis is related to initial stroke severity, infarct size, and outcome 2, 3, 4.
- The relationship between leukocytosis and stroke outcome is complex, with some studies suggesting that leukocytosis is a stress response with no independent influence on outcome 2, while others have found that leukocytosis is associated with poor outcomes, including increased mortality and functional impairment 3, 4, 5, 6.
Mechanisms and Predictors
- Leukocytosis in stroke may be caused by a sterile inflammation response, which is a pathophysiological relevant mechanism that deserves further investigation 3.
- Neutrophil to lymphocyte ratio (NL-R), lymphocyte count, eosinophil count, and eosinophil to leukocyte ratio (EoLeu-R) have been identified as predictors of outcome in stroke patients, independently of infections 3.
- Persistent leukocytosis, defined as leukocytosis lasting more than 48 hours, has been associated with poor functional outcome and higher baseline NIHSS scores 5.
Clinical Implications
- Leukocytosis at the time of neurologic deterioration after acute ischemic stroke is associated with poor outcomes and may represent a marker of greater cerebral damage through increased parenchymal inflammation 6.
- Identifying patients with persistent leukocytosis could help to prognosticate and target patients that may benefit from future anti-inflammatory interventions 5.