What are the criteria for platelet (PLT) transfusion in patients with Dengue fever?

Platelet Transfusion Criteria in Dengue Fever

Prophylactic platelet transfusion should NOT be given to dengue patients with thrombocytopenia in the absence of active bleeding, regardless of platelet count, as it does not reduce bleeding risk and increases adverse events. 1, 2

Evidence-Based Approach to Platelet Transfusion in Dengue

When NOT to Transfuse (Most Important)

Prophylactic transfusion is contraindicated in dengue because thrombocytopenia results from increased platelet destruction rather than impaired marrow production. 1 This is a critical distinction from cancer patients with bone marrow failure, where prophylactic transfusion at 10,000/μL is standard. 3

• The landmark randomized controlled trial of 372 dengue patients demonstrated that prophylactic platelet transfusion in patients with platelets ≤20,000/μL without bleeding showed no reduction in clinical bleeding (21% vs 26%, p=0.16) but significantly increased adverse events (13 vs 2 events, p=0.0064). 2

• Adverse events included anaphylaxis, transfusion-related acute lung injury, and fluid overload requiring serious intervention. 2

• Patients with poor platelet recovery who received prophylactic transfusion were actually MORE likely to bleed (odds ratio 2.34). 4

When TO Transfuse: Therapeutic Indications Only

Platelet transfusion in dengue is indicated ONLY for:

Active Significant Bleeding

• Target platelet count ≥50,000/mm³ for patients with active bleeding. 1
• Dose: 4 units of pooled platelet concentrates or one apheresis unit. 1, 5
• Transfuse as rapidly as tolerated in urgent bleeding scenarios. 5

Invasive Procedures or Surgery

• Maintain platelet count at 40,000-50,000/mm³ for major procedures or surgery. 1
• For lumbar puncture: transfuse if platelet count <50,000/mm³. 1
• For central venous catheter placement: transfuse if platelet count <20,000/mm³. 1

Extremely Low Counts with High-Risk Features

• Consider transfusion for platelet counts <5,000/μL in observational studies. 6
• Consider for counts <20,000/μL ONLY if additional risk factors present: advanced age, hypertension, peptic ulcer disease, anticoagulant use, recent trauma/surgery. 1
• Fever >38°C is a risk factor that may warrant higher transfusion thresholds in the presence of other bleeding risks. 1, 7

Practical Clinical Algorithm

Step 1: Assess for Active Bleeding

• If YES and significant: Transfuse to maintain platelets ≥50,000/mm³. 1
• If NO: Proceed to Step 2.

Step 2: Assess Need for Invasive Procedures

• If major procedure/surgery planned: Transfuse to maintain 40,000-50,000/mm³. 1
• If lumbar puncture: Transfuse if <50,000/mm³. 1
• If central line: Transfuse if <20,000/mm³. 1
• If NO procedures: Proceed to Step 3.

Step 3: Assess Platelet Count and Risk Factors

• If platelets >20,000/μL: Do NOT transfuse prophylactically. 1, 2
• If platelets 5,000-20,000/μL without risk factors: Supportive care only (fluids, avoid NSAIDs/aspirin, monitor). 1, 6
• If platelets <5,000/μL OR <20,000/μL with multiple high-risk features: Consider transfusion with clinical judgment. 1, 6

Supportive Care Protocol (Standard Management)

For all dengue patients with thrombocytopenia without bleeding:

• Adequate fluid therapy. 1
• Fever and pain management (avoid NSAIDs/aspirin). 1
• Serial platelet count monitoring every 12-24 hours. 1
• Bed rest and close observation for bleeding signs. 6

Critical Pitfalls to Avoid

Do not apply cancer/leukemia guidelines (10,000/μL prophylactic threshold) to dengue patients. 1 The pathophysiology is fundamentally different—dengue causes peripheral platelet destruction and consumption, not marrow failure. 1

Do not transfuse based solely on platelet count. 3, 1 A restrictive strategy based on clinical features proved safe in 350 dengue patients, with only 9 (2.6%) requiring transfusion. 6

Recognize that platelet transfusion in dengue may paradoxically increase bleeding risk in patients with poor platelet recovery, possibly due to immune-mediated mechanisms or fluid overload. 4

Fever alone (>38°C) is NOT an indication for prophylactic transfusion in dengue, though it may lower the threshold if other bleeding risk factors are present. 1, 7

Transfusion Dosing When Indicated

• Standard dose: 4 units pooled platelet concentrates or one apheresis unit. 1, 5
• Expected increment: 5-10 × 10⁹/L per unit or >30 × 10⁹/L per apheresis unit. 5
• Have additional units available if bleeding persists. 1
• Obtain post-transfusion platelet count to confirm adequate response. 1