What is the cause of leukocytosis (elevated white blood cell count) in a 28-year-old male?

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From the Guidelines

Leukocytosis in a 28-year-old male should be immediately evaluated for hyperleukocytosis, defined as a WBC count more than 100 x 10^9/L, and managed with hydroxyurea at dosages up to 50 to 60 mg/kg per day to reduce the risk of hemorrhagic events, tumor lysis syndrome, and infections, as recommended by the European LeukemiaNet 1. When approaching a patient with leukocytosis, it's crucial to consider the potential for an underlying hematologic malignancy, such as acute myeloid leukemia, which can present with hyperleukocytosis. The management of hyperleukocytosis is focused on reducing the WBC count to prevent complications such as leukostasis, pulmonary infiltrates, or retinal and cerebral hemorrhages.

  • Key considerations in the management of leukocytosis include:
    • Immediate medical treatment for hyperleukocytosis with leukostasis or signs of end-organ damage
    • Use of hydroxyurea to lower WBC count, with dosages adjusted based on response
    • Prevention of tumor lysis syndrome through hydration, control of uric acid production, and management of urine pH
    • Avoidance of excessive red blood cell transfusions until WBC count is reduced to prevent increased blood viscosity The initial evaluation should include a complete blood count with differential, and further testing should be guided by clinical presentation and suspected underlying cause. However, in the context of significant leukocytosis, the priority is to rapidly reduce the WBC count to prevent life-threatening complications, as outlined in the recommendations from the European LeukemiaNet 1.

From the FDA Drug Label

Hematological changes Isolated cases of agranulocytosis (< 500/mm3) have been reported, most of them after 10 days of treatment and following total doses of 20 grams or more. Investigations Other rarely observed adverse reactions (<0. 1%) include abdominal pain, agranulocytosis, allergic pneumonitis, anaphylaxis, basophilia, biliary lithiasis, bronchospasm, colitis, dyspepsia, epistaxis, flatulence, gallbladder sludge, glycosuria, hematuria, jaundice, leukocytosis, lymphocytosis, monocytosis, nephrolithiasis, palpitations, a decrease in the prothrombin time, renal precipitations, seizures, and serum sickness

Leukocytosis is listed as a rarely observed adverse reaction (<0.1%) in the ceftriaxone drug label 2.

From the Research

Leukocytosis in a 28-year-old Male

  • Leukocytosis is defined as a white blood cell count greater than 11,000/mcL in nonpregnant adults 3
  • The differential diagnosis of leukocytosis can be broadly divided into primary malignant diseases and secondary causes that are expected physiologic responses of the bone marrow 3
  • Infections and chronic inflammatory conditions are common causes of secondary leukocytosis 3, 4
  • A thorough history, physical examination, and peripheral blood smear are the basis of the initial evaluation 3

Causes of Leukocytosis

  • Physical stress (e.g., from seizures, anesthesia or overexertion) and emotional stress can also elevate white blood cell counts 5
  • Medications commonly associated with leukocytosis include corticosteroids, lithium and beta agonists 5
  • Increased eosinophil or basophil counts, resulting from a variety of infections, allergic reactions and other causes, can lead to leukocytosis in some patients 5

Evaluation and Management

  • A repeat complete blood count with peripheral smear may provide helpful information, such as types and maturity of white blood cells, uniformity of white blood cells, and toxic granulations 4
  • Symptoms suggestive of a hematologic malignancy include fever, weight loss, bruising, or fatigue 4
  • If malignancy cannot be excluded or another more likely cause is not suspected, referral to a hematologist/oncologist is indicated 4
  • White blood cell counts above 100,000 per mm3 (100 x 10(9) per L) represent a medical emergency because of the risk of brain infarction and hemorrhage 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Evaluation of Patients with Leukocytosis.

American family physician, 2015

Research

Leukocytosis: basics of clinical assessment.

American family physician, 2000

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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