What is the diagnosis and treatment for a patient with leukocytosis?

Diagnosis: Polycythemia with Mild Leukocytosis

This patient presents with polycythemia (elevated RBC, hemoglobin, and hematocrit) accompanied by mild leukocytosis, NOT a primary leukocyte disorder requiring emergency intervention. The WBC of 14.3 × 10⁹/L is only mildly elevated and does not approach thresholds requiring urgent treatment 1, 2.

Critical Distinction from Emergency Leukocytosis

• This WBC count does NOT constitute a medical emergency. Emergency intervention is only indicated when WBC >100,000/μL due to risks of leukostasis, tumor lysis syndrome, and hemorrhage 1, 3.
• The National Comprehensive Cancer Network reserves immediate treatment for WBC >200-300 × 10⁹/L with symptoms of leukostasis 2.
• WBC counts can physiologically double within hours from stress, exercise, trauma, or emotional factors without pathologic significance 4.

Primary Diagnosis: Polycythemia Workup Required

The dominant abnormality is the elevated hematocrit of 50.9% (normal male <52%, female <48%), hemoglobin 16.6 g/dL, and RBC 5.91 × 10¹²/L. This constellation requires evaluation for:

• Primary polycythemia vera (myeloproliferative disorder with JAK2 mutation testing indicated)
• Secondary polycythemia from chronic hypoxia (COPD, sleep apnea, high altitude), smoking, dehydration, or erythropoietin-secreting tumors
• Relative polycythemia from volume depletion

The mild concurrent leukocytosis may represent a reactive process or be part of a myeloproliferative disorder if polycythemia vera is confirmed 4, 3.

Immediate Diagnostic Workup

• Obtain peripheral blood smear to assess cell morphology, maturity, and rule out left shift or abnormal cells 4, 5.
• Comprehensive metabolic panel including liver enzymes, renal function, and electrolytes to assess organ function and hydration status 1.
• Inflammatory markers (CRP, ESR) to evaluate for inflammatory or infectious causes of the leukocytosis 1.
• Arterial blood gas to assess for hypoxemia driving secondary polycythemia.
• JAK2 V617F mutation testing if polycythemia vera is suspected.
• Erythropoietin level (low in polycythemia vera, high in secondary causes).

Management of Mild Leukocytosis Component

• No immediate intervention required for WBC 14.3 × 10⁹/L unless accompanied by fever, infection symptoms, or signs of hematologic malignancy 1, 2.
• Rule out common benign causes: recent physical stress, medications (corticosteroids, lithium, beta-agonists), smoking, obesity, or chronic inflammatory conditions 4, 3.
• Repeat CBC with differential in 2-4 weeks if no clear etiology identified to assess for progression 4, 5.

Red Flags Requiring Hematology Referral

• Constitutional symptoms: fever, unintentional weight loss >10% in 6 months, night sweats, or significant fatigue 2, 5.
• Splenomegaly, hepatomegaly, or lymphadenopathy on examination 3, 5.
• Abnormal peripheral smear showing immature cells, blasts, or dysplastic features 4, 5.
• Progressive leukocytosis with >50% increase over 2 months 2, 6.
• Concurrent unexplained anemia or thrombocytopenia suggesting bone marrow disorder 3, 5.

Critical Pitfalls to Avoid

• Do not treat the WBC elevation in isolation without identifying the underlying cause 4, 3.
• Do not overlook the polycythemia as the primary abnormality requiring investigation.
• Do not delay hematology referral if peripheral smear shows abnormal or immature cells 5.
• Do not assume infection based solely on mild leukocytosis without fever or localizing symptoms 4, 7.