Can a Deep Vein Thrombosis (DVT) and a pulmonary embolus cause a leukocytosis to 20,000?

Can DVT and PE Cause Leukocytosis to 20,000?

No, DVT and pulmonary embolism alone do not typically cause leukocytosis to 20,000/mm³. A WBC count this elevated should prompt investigation for alternative or concurrent diagnoses such as infection, malignancy, or other inflammatory conditions.

Evidence for Leukocytosis in Acute PE

The most direct evidence comes from a retrospective study of 386 patients with acute PE that specifically examined this question 1:

• Among patients with PE and no other identifiable cause of leukocytosis, only 20% (52 of 266 patients) had WBC counts >10,000/mm³ 1
• Critically, none of these patients had WBC counts ≥20,000/mm³ 1
• The presence or absence of pulmonary hemorrhage/infarction syndrome did not significantly affect the degree of leukocytosis (17% vs 24%) 1

Clinical Implications

When to Suspect PE Despite Leukocytosis

While modest leukocytosis (WBC 10,000-15,000/mm³) may accompany PE, a WBC count of 20,000/mm³ should not be attributed to PE alone 1. The presence of marked leukocytosis should not dissuade clinicians from pursuing PE diagnosis if clinical suspicion exists, but it mandates investigation for other causes 1.

Prognostic Factors Supporting PE Diagnosis

Moderate-certainty evidence identifies leukocytosis as a probable prognostic factor for VTE in hospitalized medical patients, but this refers to modest elevations, not counts reaching 20,000/mm³ 2. Other supportive findings include:

• Elevated D-dimer, C-reactive protein, and fibrinogen levels 2
• Tachycardia, fever, and leg edema 2
• Thrombocytosis (not thrombocytopenia) 2
• Previous VTE history, malignancy, or critical illness 2

Alternative Diagnoses to Consider

A WBC count of 20,000/mm³ in a patient with suspected VTE requires evaluation for:

• Infection/sepsis - including septic thrombophlebitis or septic pulmonary emboli, which can mimic PE 2
• Malignancy - particularly hematologic malignancies, as cancer is strongly associated with VTE but can independently cause marked leukocytosis 2
• Inflammatory conditions - such as inflammatory bowel disease, which carries increased VTE risk but also causes leukocytosis 2
• Concurrent pneumonia - fever, leukocytosis, and pulmonary infiltrates can occur with both conditions 2

Common Pitfalls

• Attributing marked leukocytosis solely to PE/DVT - This can delay diagnosis of serious concurrent conditions like infection or malignancy 1
• Dismissing PE diagnosis due to leukocytosis - While a WBC of 20,000/mm³ is atypical for PE alone, it does not exclude the diagnosis if other clinical features are present 1
• Overlooking cancer screening - Patients with idiopathic VTE develop subsequent malignancies in approximately 10% of cases, though extensive workup beyond careful history, physical examination, chest X-ray, and complete blood count is not recommended 2

Diagnostic Approach

When encountering a patient with suspected VTE and WBC 20,000/mm³:

1. Proceed with standard VTE diagnostic workup if clinical suspicion warrants (Wells score, D-dimer, imaging) 2, 3
2. Simultaneously investigate alternative causes of marked leukocytosis through blood cultures, inflammatory markers, and imaging as clinically indicated 2
3. Consider malignancy evaluation if no obvious infectious or inflammatory source is identified, particularly in cases of unprovoked VTE 2