What is the appropriate management for a 53-year-old female with leukocytosis (elevated white blood cell count) and a normal hematocrit?

Management of Leukocytosis in a 53-Year-Old Female

The immediate priority is to determine whether this leukocytosis represents infection, inflammation, or a primary hematologic disorder through peripheral blood smear examination and assessment for clinical signs of infection or systemic illness. 1, 2

Immediate Clinical Assessment

The white blood cell count of 14,300/mm³ exceeds the threshold of 14,000 cells/mm³, which carries a likelihood ratio of 3.7 for bacterial infection even without fever. 1, 2 This mandates immediate investigation:

• Obtain a peripheral blood smear immediately to examine white blood cell morphology, assess for left shift (band neutrophils ≥16% or ≥1500 cells/mm³), and rule out malignant cells. 2 A left shift increases the likelihood ratio for bacterial infection to 14.5. 1

• Assess for clinical signs of infection including fever, localizing symptoms (respiratory, urinary, abdominal), or signs of sepsis, as leukocytosis without fever does not exclude infection, particularly in older adults. 1, 2

• Obtain blood cultures and site-specific cultures before initiating antibiotics if infection is suspected based on clinical presentation. 3, 1

Diagnostic Workup

Essential Laboratory Tests

• Complete blood count with differential to characterize which cell line is elevated (neutrophils, lymphocytes, eosinophils, or basophils). 2

• Comprehensive metabolic panel to assess organ function and monitor for potential complications. 2

• Site-specific evaluation based on symptoms:

  • Urinalysis and urine culture if urinary symptoms present 2
  • Chest imaging if respiratory symptoms present 2
  • CT imaging for suspected intra-abdominal infections 2

Distinguishing Primary vs. Secondary Causes

Primary bone marrow disorders should be suspected if any of the following are present: 4

• Extremely elevated white blood cell counts (>100,000/mm³)
• Concurrent abnormalities in red blood cell or platelet counts
• Weight loss, bleeding, bruising
• Liver, spleen, or lymph node enlargement
• Immunosuppression

The normal hematocrit of 50.9% in this patient argues against polycythemia vera, which classically presents with erythrocytosis (hematocrit >49% in men or >48% in women), leukocytosis, and thrombocytosis. 5, 6

Management Based on Etiology

If Infection is Identified

• Initiate prompt empiric broad-spectrum antimicrobial therapy based on the likely source of infection. 1

• Avoid treating asymptomatic patients with antibiotics based solely on mildly elevated WBC counts, as this leads to unnecessary antibiotic use. 2

If Primary Hematologic Disorder is Suspected

• Flow cytometry should be considered if lymphoproliferative disorder is suspected based on morphology. 2

• Bone marrow examination may be necessary if peripheral smear suggests acute leukemia or chronic myeloproliferative disorder. 4

If Reactive/Benign Leukocytosis

Most leukocytosis is due to relatively benign conditions including infections, inflammatory processes, physical or emotional stress, or medications (corticosteroids, lithium, beta agonists). 4 Management focuses on treating the underlying condition.

Critical Thresholds and Red Flags

White blood cell counts above 100,000/mm³ represent a medical emergency due to risk of brain infarction and hemorrhage from leukostasis. 4 This patient's count of 14,300/mm³ does not meet this threshold.

Common Pitfalls to Avoid

• Do not overlook the significance of absolute neutrophil count elevation when total WBC count is only mildly elevated. 2

• Do not assume absence of infection based solely on lack of fever, especially in older adults. 1, 2

• Do not delay peripheral smear examination, as morphology provides critical diagnostic information that cannot be obtained from automated counts alone. 2, 4