What is the significance of an elevated white blood cell (WBC) count with elevated absolute neutrophil count (ANC)?

From the Guidelines

An elevated white blood cell count with elevated absolute neutrophils is a significant finding that warrants immediate attention and further investigation to determine the underlying cause, with a focus on identifying potential bacterial infections, inflammatory processes, or other serious conditions such as leukemia, as indicated by the most recent guidelines 1.

Key Considerations

• The presence of an elevated WBC count or a left shift (percentage of band neutrophils or metamyelocytes) is a critical indicator of potential bacterial infection, especially in vulnerable populations such as older adults in long-term care facilities 1.
• A complete history and physical examination should be performed, followed by additional testing which may include blood cultures, imaging studies, or specific tests based on symptoms to identify the underlying cause of the elevated white blood cell count and neutrophils.
• The degree of elevation in white blood cell count and neutrophil levels can provide clues about the severity of the condition, with very high levels potentially indicating more serious issues such as leukostasis, which can cause organ compromise 1.

Diagnostic Approach

• A CBC count, including peripheral WBC and differential cell counts, should be performed promptly in patients suspected of having an infection, consistent with local standards of practice 1.
• The presence of an elevated WBC count (WBC count, 14,000 cells/mm3) or a left shift warrants a careful assessment for bacterial infection, with or without fever 1.

Management

• No specific medication is recommended without identifying the underlying cause of the elevated white blood cell count and neutrophils.
• If infection is confirmed, appropriate antibiotics would be prescribed based on the type of infection and sensitivity testing.
• For non-infectious causes, treating the underlying condition is essential to reduce morbidity, mortality, and improve quality of life, as emphasized by recent guidelines 1.

From the Research

Elevated White Count and Absolute Neutrophils

• An elevated white blood cell count, including absolute neutrophils, can have various etiologies, including malignant and nonmalignant causes 2.
• The leukocyte differential may show eosinophilia in parasitic or allergic conditions, or it may reveal lymphocytosis in childhood viral illnesses 2.
• Leukocytosis is a common sign of infection, particularly bacterial, and should prompt physicians to identify other signs and symptoms of infection 2.
• Stressors capable of causing an acute leukocytosis include surgery, exercise, trauma, and emotional stress 2.
• Other nonmalignant etiologies of leukocytosis include certain medications, asplenia, smoking, obesity, and chronic inflammatory conditions 2.

Clinical Features and Outcome

• Unexplained or persistent leukocytosis is an increasing common cause of consultation to infectious disease physicians 3.
• Patients with unexplained leukocytosis may appear to be in a state of continued inflammation, recently described as the persistent inflammation-immunosuppression and catabolism syndrome (PICS) 3.
• The hospital course of such patients is frequently prolonged and associated with extensive use of empiric broad-spectrum antibiotics 3.
• Peak total leukocyte count and peak percentage early myelocytic ("band") leukocytes can be useful in assessing the severity of leukocytosis 3.

Diagnostic Approach

• The normal reaction of bone marrow to infection or inflammation leads to an increase in the number of white blood cells, predominantly polymorphonuclear leukocytes and less mature cell forms (the "left shift") 4.
• Physical stress and emotional stress can also elevate white blood cell counts 4.
• Medications commonly associated with leukocytosis include corticosteroids, lithium, and beta agonists 4.
• Primary bone marrow disorders should be suspected in patients who present with extremely elevated white blood cell counts or concurrent abnormalities in red blood cell or platelet counts 4.

Prognostic Implications

• Elevated leukocyte count, including neutrophil and monocyte counts, may be a harbinger of increased systemic inflammation and subclinical disease 5.
• High but normal leukocyte counts at baseline predict increased cardiovascular and noncardiovascular mortality in older adults 5.
• Leukocyte count correlates positively with genuine markers of systemic inflammation like C-reactive protein and interleukin 6 5.
• Leukocyte counts have a stronger prognostic ability with regard to total and cardiovascular mortality than total cholesterol or low-density lipoproteins 5.