From the Guidelines
The initial workup for a patient with leukocytosis should begin with a thorough history and physical examination, followed by a complete blood count with differential, comprehensive metabolic panel, and other tests as indicated by the clinical presentation, such as urinalysis, blood cultures, chest X-ray, and inflammatory markers. This approach is supported by the most recent and highest quality study, which emphasizes the importance of a comprehensive initial evaluation to identify potential causes of leukocytosis 1. The differential count will help determine which cell line is elevated, providing important diagnostic clues.
Key Components of the Initial Workup
- Complete blood count with differential to characterize the elevated white blood cells
- Comprehensive metabolic panel to assess for any underlying metabolic abnormalities
- Urinalysis to evaluate for signs of infection or inflammation
- Blood cultures if infection is suspected
- Chest X-ray to evaluate for any pulmonary abnormalities
- Inflammatory markers (ESR, CRP) to assess for signs of inflammation
Additional Tests as Indicated
Depending on the clinical presentation, additional tests may be warranted, such as:
- Peripheral blood smear to evaluate cell morphology and rule out leukemia
- Flow cytometry if lymphocytosis is present to distinguish between reactive and malignant causes
- Specific tests for suspected conditions, such as hepatitis panel or bone marrow biopsy
Importance of Tailoring the Workup
The workup should be tailored to the patient's presentation, as leukocytosis can result from various conditions, including infections, inflammation, malignancies, medications, and physiologic stress. Timing of follow-up testing depends on the severity of leukocytosis and clinical stability, with more urgent evaluation needed for very high counts (>30,000/μL) or signs of serious illness. This approach is supported by the NCCN guidelines for pediatric acute lymphoblastic leukemia, which emphasize the importance of a comprehensive initial evaluation and tailored workup 1.
From the Research
Initial Workup for Leukocytosis
The initial workup for a patient with leukocytosis (elevated White Blood Cell count) includes:
- A thorough history and physical examination to identify potential causes of leukocytosis, such as infections, chronic inflammatory conditions, or primary malignant diseases 2, 3, 4, 5
- A peripheral blood smear to evaluate the types and maturity of white blood cells, uniformity of white blood cells, and toxic granulations 2, 4, 6
- A repeat complete blood count (CBC) with differential to confirm the diagnosis and provide more information about the types of white blood cells present 4
Identifying Potential Causes
Potential causes of leukocytosis can be broadly divided into:
- Primary malignant diseases, such as acute or chronic leukemias 2, 3, 5
- Secondary causes, such as infections, chronic inflammatory conditions, physical stress, emotional stress, or medications 2, 3, 4
- Other nonmalignant etiologies, such as certain medications, asplenia, smoking, obesity, or chronic inflammatory conditions 3, 4
Further Evaluation
Further evaluation may be necessary if:
- The patient presents with constitutional symptoms, such as fever, weight loss, bruising, or fatigue, which may suggest a hematologic malignancy 2, 4
- The peripheral blood smear shows abnormal results, such as blasts, which may indicate acute leukemia 6
- The patient has a very high white blood cell count, which may represent a medical emergency 3 In such cases, referral to a hematology subspecialist or hematologist/oncologist may be indicated for further evaluation and management 2, 4, 5