What is the diagnosis for a patient with neutropenia?

Normal Neutrophil Count - No Diagnosis of Neutropenia

A segmented neutrophil count of 48.3% is within normal limits and does not indicate neutropenia or any specific diagnosis. To determine if neutropenia exists, you must calculate the absolute neutrophil count (ANC), which requires the total white blood cell count multiplied by the neutrophil percentage.

Understanding the Numbers

• Neutropenia is defined as an ANC <1,500 cells/µL (or <500 cells/µL for severe neutropenia requiring urgent intervention) 1
• A percentage alone (48.3%) cannot establish a diagnosis - you need the absolute count 2
• Normal neutrophil percentage ranges from approximately 40-70% of total white blood cells 2

What You Need to Calculate ANC

ANC = Total WBC count × (% neutrophils/100)

For example:

• If WBC = 7,000 cells/µL and neutrophils = 48.3%, then ANC = 3,381 cells/µL (normal)
• If WBC = 2,000 cells/µL and neutrophils = 48.3%, then ANC = 966 cells/µL (mild neutropenia) 3

Clinical Significance by ANC Level

Normal Range (ANC ≥1,500 cells/µL)

• No increased infection risk 2
• Routine monitoring sufficient if asymptomatic 2

Mild Neutropenia (ANC 1,000-1,500 cells/µL)

• Minimal infection risk 3
• Monitor if persistent or symptomatic 4

Moderate Neutropenia (ANC 500-1,000 cells/µL)

• Increased infection susceptibility 3
• Requires investigation of underlying cause 5

Severe Neutropenia (ANC <500 cells/µL)

• High risk for life-threatening bacterial and fungal infections 1
• Requires urgent evaluation and empiric broad-spectrum antibiotics if febrile 1
• Hospitalization indicated for high-risk patients (MASCC score <21, prolonged neutropenia >7 days, or ANC <100 cells/µL) 1

When to Investigate Further

Even with a normal percentage, obtain complete blood count with differential and calculate ANC if the patient has:

• Fever (temperature >38.3°C or >101°F) 1
• Recurrent infections (sinopulmonary, skin, opportunistic organisms) 1
• Recent chemotherapy or immunosuppressive therapy 1, 6
• Medication exposure to drugs causing myelosuppression (antibiotics >2 weeks, especially beta-lactams) 7
• Autoimmune conditions or malignancy 1, 5

Common Pitfall

Do not confuse neutrophil percentage with absolute neutrophil count. A patient can have a normal or even elevated percentage but still be neutropenic if the total WBC is low 2, 3. Always calculate the ANC before determining clinical significance.