From the Guidelines
Thrombocytopenia in dengue fever is primarily caused by direct suppression of bone marrow by the dengue virus, immune-mediated destruction of platelets, and increased peripheral sequestration of platelets. The mechanisms leading to thrombocytopenia in dengue fever are complex and multifactorial. According to the most recent evidence 1, thrombocytopenia is a significant predictor of dengue, with a likelihood ratio (LR) of 5, indicating that its presence strongly increases the probability of a diagnosis of dengue.
Key Mechanisms
- Direct suppression of bone marrow by the dengue virus, which impairs platelet production
- Immune-mediated destruction of platelets through antibody formation against them
- Increased peripheral sequestration of platelets in the spleen and liver, contributing to their decreased circulation
- Platelet consumption increases during dengue infection due to disseminated intravascular coagulation and endothelial damage
- Apoptosis (programmed cell death) of platelets is also enhanced during infection
- Cross-reactivity between anti-dengue antibodies and platelets further accelerates destruction These mechanisms collectively result in the characteristic low platelet counts seen in dengue patients, which typically reach their lowest point 3-7 days after symptom onset and gradually recover during the convalescent phase without specific treatment beyond supportive care 1.
Clinical Implications
- Thrombocytopenia is a critical factor in the diagnosis and management of dengue fever
- Early recognition and monitoring of thrombocytopenia are essential to prevent and manage potential complications, such as bleeding and severe hemorrhage
- Supportive care, including fluid replacement and transfusions, may be necessary to manage thrombocytopenia and prevent adverse outcomes.
From the Research
Mechanisms of Thrombocytopenia in Dengue Fever
The exact mechanisms of thrombocytopenia in dengue fever are complex and involve multiple factors, including:
- Platelet activation
- Procoagulant and anticoagulant arms of the coagulation system
- Complement
- Cytokines
- Endothelial cells 2 These mechanisms lead to a decrease in platelet count, which can result in bleeding manifestations in some patients.
Predictors of Poor Platelet Recovery
Studies have identified several predictors of poor platelet recovery in dengue patients with thrombocytopenia, including:
- Age
- White cell count
- Day of illness at study enrollment 3 Patients with these predictors are more likely to have poor platelet recovery, which can increase the risk of bleeding.
Role of Platelet Transfusion
Platelet transfusion is commonly used in the management of dengue patients with thrombocytopenia, but its effectiveness is still debated. Some studies suggest that platelet transfusion can increase the risk of bleeding in patients with poor platelet recovery 3, while others found that it can improve platelet count increments at 24 and 72 hours 4. However, platelet transfusion is not without risks, and significant side effects have been reported 4.
Clinical Outcomes
The clinical outcomes of dengue patients with thrombocytopenia vary depending on several factors, including the severity of thrombocytopenia and the presence of bleeding manifestations. Patients with severe thrombocytopenia are at higher risk of bleeding, and platelet transfusion may be necessary in these cases 5. However, the decision to transfuse platelets should be made on a case-by-case basis, taking into account the individual patient's risk factors and clinical condition.