What can cause an elevated absolute neutrophil count (ANC) in a 9‑year‑old child?

Elevated Absolute Neutrophil Count in a 9-Year-Old Child

An ANC of 9.6 × 10³/µL in a 9-year-old represents neutrophilia and is most commonly caused by acute bacterial infection, physiologic stress response, or corticosteroid exposure—each requiring specific clinical correlation to guide management. 1

Understanding the Elevation

The normal ANC range is typically 2.0–7.5 × 10⁹/L, making this child's value of 9.6 × 10⁹/L clearly elevated above the upper limit of normal. 1, 2 This represents the opposite end of the spectrum from neutropenia (ANC <0.5 × 10⁹/L) and indicates an active process stimulating neutrophil production or release. 1

Primary Causes of Neutrophilia in Children

Acute Infection or Inflammation

• Bacterial infections are the most common cause of neutrophilia in children, particularly those involving gram-negative organisms or significant tissue invasion. 1, 3
• The neutrophil count rises significantly during acute bacterial infections as part of the innate immune response. 1
• Toxic granulation in neutrophils appears on blood smear during bacterial infection and is as sensitive as elevated ANC in predicting bacterial infection. 3

Physiologic Stress Response

• Physical stress, emotional stress, exercise, or acute illness can cause transient neutrophilia through demargination of neutrophils from vessel walls into the circulation. 1
• This mechanism produces rapid elevation without increased production and typically resolves within hours to days once the stressor is removed. 1

Medication-Induced Neutrophilia

• Corticosteroid administration (endogenous or exogenous) commonly elevates neutrophil counts by reducing margination and apoptosis while increasing bone marrow release. 1
• Other medications that can cause neutrophilia include G-CSF, lithium, and epinephrine. 1

Malignancy Considerations (Less Common in Children)

• Primary hematologic malignancies such as chronic myeloid leukemia can present with persistent neutrophilia, though this is rare in the pediatric population. 1
• Solid tumors may cause paraneoplastic neutrophilia through cytokine production (G-CSF, GM-CSF). 1

Essential Diagnostic Evaluation

Immediate Clinical Assessment

• Review for signs and symptoms of acute infection: fever, localized pain, respiratory symptoms, urinary symptoms, or skin/soft tissue changes. 1
• Obtain detailed medication history, particularly recent corticosteroid use, G-CSF administration, or other medications known to affect neutrophil counts. 1
• Assess for recent physical or emotional stress, including trauma, surgery, or significant illness. 1

Laboratory Context

• Review the complete blood count in its entirety—concurrent thrombocytosis or polycythemia would suggest a myeloproliferative disorder rather than reactive neutrophilia. 1, 2
• Examine the peripheral blood smear for toxic granulation, vacuolation, and Döhle bodies, which indicate bacterial infection when present. 3
• Consider inflammatory markers (CRP, ESR) if infection is suspected but not clinically obvious. 1

Follow-Up Testing if Persistent

• If neutrophilia persists without clear cause after 2–4 weeks, hematology referral is indicated for evaluation of myeloproliferative disorders. 1
• Advanced testing may include JAK2 mutation testing, BCR-ABL testing, and bone marrow biopsy for unexplained persistent neutrophilia. 1

Management Algorithm

Step 1: Identify and Treat Acute Causes

• If bacterial infection is suspected or confirmed, initiate appropriate antimicrobial therapy based on clinical presentation and culture results. 1, 3
• Discontinue or taper corticosteroids if possible when medication-induced neutrophilia is identified. 1
• Address underlying physiologic stressors (pain control, anxiety management, treatment of acute illness). 1

Step 2: Monitor and Reassess

• Repeat CBC in 1–2 weeks if no acute illness is identified to determine whether the elevation is transient or persistent. 1
• If neutrophilia persists beyond 4 weeks without explanation, refer to hematology for myeloproliferative disorder workup. 1

Step 3: Document Trends

• Serial ANC measurements are more informative than isolated values in determining clinical significance. 2
• Stable mild elevation may represent benign ethnic neutrophilia or chronic stress response, while progressive elevation warrants more aggressive investigation. 1

Critical Pitfalls to Avoid

• Do not overlook the complete blood count context—isolated neutrophilia has different implications than pancytosis or combined cytopenias. 2
• Do not assume infection without clinical correlation—many cases of neutrophilia are physiologic or medication-related and resolve spontaneously. 1
• Do not delay hematology referral for unexplained persistent neutrophilia, as early detection of myeloproliferative disorders improves outcomes. 1
• Do not ignore the peripheral smear—toxic granulation and other morphologic changes provide critical diagnostic information about the underlying cause. 3