Do asplenic (asplenetic, without a spleen) patients experience severe leukocytosis (elevated white blood cell count)?

From the Guidelines

Asplenic patients can develop leukocytosis, but it is typically mild to moderate rather than severe, with baseline elevation in white blood cell counts usually ranging from 12,000-20,000 cells/μL, which represents a normal physiological response to the absence of the spleen. This occurs because the spleen normally sequesters and removes aging or abnormal white blood cells from circulation. Without this filtering function, these cells remain in the bloodstream longer, resulting in higher baseline counts. However, truly severe leukocytosis (>30,000-50,000 cells/μL) in asplenic patients should not be attributed solely to their asplenic state and warrants investigation for other causes such as infection, inflammation, malignancy, or other pathological processes, as supported by the guidelines for infection prevention in asplenic patients 1.

Some key points to consider in the management of asplenic patients include:

• Vaccination against encapsulated bacteria, such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, is crucial to prevent overwhelming post-splenectomy infection (OPSI) 1.
• The risk of OPSI is highest in the first year after splenectomy, especially in young children, but remains elevated for more than 10 years and probably for life 1.
• Annual immunization against seasonal flu is recommended for all asplenic patients over 6 months of age to decrease the risk of secondary bacterial infection, including pneumococcal infection 1.
• Asplenic patients should be given an antibiotic supply in the event of any sudden onset of unexplained fever, malaise, chills, or other constitutional symptoms, especially when medical review is not readily accessible 1.

It is essential for clinicians to be aware of the baseline elevation in white blood cell counts in asplenic patients to avoid unnecessary workups but still maintain vigilance for significant elevations beyond the expected post-splenectomy range, as these patients are particularly vulnerable to overwhelming infections that may present with marked leukocytosis. The most recent and highest quality study on this topic is from 2018 1, which provides guidelines for the prevention and treatment of infection in patients with an absent or dysfunctional spleen.

In terms of specific management, the study recommends vaccination against Streptococcus pneumoniae with PCV13, followed by PPSV23 6-12 weeks later, and revaccination every 6 years 1. Additionally, asplenic patients should be vaccinated with conjugated HiB vaccine and tetravalent conjugated meningococcal vaccine, including activity against serogroups A, C, W, Y (MenACWY) 1.

Overall, while asplenic patients can develop leukocytosis, it is typically mild to moderate, and severe leukocytosis warrants investigation for other causes. Clinicians should be aware of the baseline elevation in white blood cell counts and maintain vigilance for significant elevations, while also following guidelines for infection prevention and management in asplenic patients 1.

From the Research

Asplenic Patients and Leukocytosis

• There is no direct evidence in the provided studies to suggest that asplenic patients experience severe leukocytosis (elevated white blood cell count) as a result of their condition.
• The studies focus on the increased risk of infections, particularly those caused by encapsulated bacteria, and the importance of preventive measures such as vaccination and antibiotic prophylaxis 2, 3, 4, 5, 6.
• The spleen's role in regulating immune responses and blood filtration is highlighted, and its absence or dysfunction can lead to increased susceptibility to severe and invasive infections 2.
• However, none of the studies specifically address the topic of leukocytosis in asplenic patients, suggesting that this may not be a well-studied or significant aspect of the condition.

Infection Risk and Prevention

• Asplenic patients are at a significantly increased risk of overwhelming infection, particularly involving encapsulated bacteria such as Streptococcus pneumoniae and Haemophilus influenzae 3, 4, 5.
• Preventive strategies, including immunoprophylaxis, antibiotic prophylaxis, and education, are crucial in reducing the risk of infection in asplenic patients 3, 4, 5, 6.
• Vaccination against specific pathogens, such as S. pneumoniae, Haemophilus influenzae type b, and Neisseria meningitidis, is recommended for asplenic patients 3, 4, 5, 6.