Can erythrocytosis, hyperhemoglobinemia, elevated hematocrit, leukopenia, and lymphocytosis in a pediatric patient under 10 years old be caused by dengue fever due to plasma leakage?

Can Dengue Cause These Hematology Results Through Plasma Leakage?

Yes, dengue fever can absolutely cause erythrocytosis, hyperhemoglobinemia, elevated hematocrit, leukopenia, and lymphocytosis in a pediatric patient under 10 years old through plasma leakage—this constellation of findings is characteristic of dengue's critical phase.

Mechanism of Hematological Changes in Dengue

Plasma leakage is the hallmark pathophysiological mechanism in dengue that directly causes hemoconcentration, manifesting as elevated hematocrit, increased hemoglobin, and relative erythrocytosis 1, 2. This occurs when capillary permeability increases, allowing plasma to leak into extravascular spaces while red blood cells remain in the intravascular compartment, concentrating the cellular components 3, 1.

Expected Hematological Pattern

The specific findings you describe align precisely with dengue's critical phase:

• Rising hematocrit with concurrent thrombocytopenia is a key warning sign of severe dengue and indicates ongoing plasma leakage 1, 2, 4
• Hematocrit increases of >20% from baseline signal significant plasma leakage requiring close monitoring and potential hospitalization 2
• Leukopenia is characteristic of dengue infection and occurs due to bone marrow suppression and viral effects on white blood cell production 5, 6
• Lymphocytosis, particularly atypical lymphocytosis, can occur in dengue and is consistent with viral infection 3, 5

Critical Phase Recognition (Days 3-7)

The critical phase typically occurs on days 3-7 of illness when plasma leakage is most pronounced 1, 2. During this period:

• Hematocrit monitoring becomes essential as rising values indicate worsening plasma leakage 1, 2
• Platelet counts typically fall to their nadir, often <100,000/mm³ 2, 6
• Clinical fluid accumulation may manifest as ascites, pleural effusions, or both 4
• Hemodynamic instability can rapidly develop if plasma leakage is severe 1, 2

Monitoring Parameters for This Patient

Daily complete blood count monitoring is essential to track the trajectory of hematocrit and platelet counts 1, 2. Specifically monitor for:

• Progressive hematocrit elevation suggesting ongoing plasma leakage requiring fluid management 1, 2
• Rapidly declining platelet counts, particularly if falling below 100,000/mm³ 2, 6
• Warning signs of progression to severe disease: persistent vomiting, severe abdominal pain, mucosal bleeding, lethargy, restlessness, or hepatomegaly 1, 2, 4
• Signs of shock: tachycardia, hypotension, poor capillary refill, narrow pulse pressure ≤20 mmHg, or altered mental status 1, 2, 4

Fluid Management Considerations

For a pediatric patient with hemoconcentration from plasma leakage:

• Oral rehydration is appropriate if the child is not in shock, targeting >2,500-3,000 mL daily fluid intake adjusted for body weight 1, 2
• Avoid routine bolus intravenous fluids if the patient is hemodynamically stable, as this increases risk of fluid overload without improving outcomes 1, 4
• If dengue shock syndrome develops, administer 20 mL/kg isotonic crystalloid bolus over 5-10 minutes with immediate reassessment 1, 2, 4

Common Pitfalls to Avoid

Do not interpret rising hematocrit as a reassuring sign—it indicates worsening plasma leakage and requires intensified monitoring 1, 2. The combination of rising hematocrit with falling platelets is particularly concerning and may warrant hospitalization 2.

Avoid using aspirin or NSAIDs for fever or pain management due to increased bleeding risk; acetaminophen (paracetamol) is the only appropriate analgesic 1, 2.

Do not delay recognition of the critical phase—failure to identify days 3-7 as the high-risk period for plasma leakage and shock can result in delayed intervention 1, 2.

Rare but Important Consideration

While the hematological findings you describe are typical for dengue with plasma leakage, persistent fever beyond the expected timeframe with worsening cytopenias should raise suspicion for hemophagocytic lymphohistiocytosis (HLH), a rare but serious complication 5, 6, 7, 8. HLH in dengue presents with:

• Persistent high fever beyond the typical dengue course 7, 8
• Progressive cytopenias affecting multiple cell lines 6, 7
• Hepatosplenomegaly 6, 7
• Markedly elevated ferritin levels (often >3,000 ng/mL) 7, 8
• Elevated triglycerides 7, 8

However, this is uncommon and should only be considered if fever and cytopenias persist beyond the expected dengue timeline 7, 8.