American Board of Internal Medicine (ABIM) Certification Practice Exam

When treating newly diagnosed immune thrombocytopenic purpura, what is the first-line therapy?

1. Rituximab

2. Dexamethasone

3. Intravenous immunoglobulin

4. Platelet transfusions

The correct answer is: Dexamethasone

The first-line therapy for newly diagnosed immune thrombocytopenic purpura (ITP) is dexamethasone. This corticosteroid is commonly used due to its effectiveness in raising platelet counts by dampening the immune response that is destroying the platelets. Dexamethasone works through immunosuppressive mechanisms, which can reduce the antibodies targeting platelets, thereby allowing for increased platelet survival. In newly diagnosed cases of ITP, treatment focuses on managing symptoms and preventing bleeding, while dexamethasone provides a rapid increase in platelet count in many patients. Other treatments, while they might play a role in management for patients who do not respond to initial therapies or have chronic ITP, are not considered first-line in this context. Rituximab, intravenous immunoglobulin, and platelet transfusions can be useful in certain situations but are typically reserved for specific circumstances, such as refractory ITP or during acute situations that require rapid hemostatic support, respectively. Thus, dexamethasone remains the preferred first approach in managing newly diagnosed ITP cases.