American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the platelet count cutoff for administering tPA?

1. 150K

2. 100K

3. 50K

4. 250K

The correct answer is: 100K

The platelet count cutoff for administering tissue plasminogen activator (tPA) in the context of treating acute ischemic stroke is typically set at 100,000 platelets per microliter of blood. This threshold is important because thrombocytopenia, defined as a low platelet count, increases the risk of bleeding complications associated with the use of thrombolytics like tPA. Patients with platelet counts below this cutoff may not be candidates for tPA therapy because the potential bleeding risks outweigh the benefits of thrombolysis. In clinical practice, a platelet count of 100,000 is thus considered a safe lower limit to ensure a sufficient number of platelets are present to help prevent significant bleeding during treatment. Higher platelet counts, such as 150,000 or 250,000, do not represent a cutoff for safety but rather indicate that the patient is well within a safe range for administration. In contrast, a cutoff at 50,000 would be too low, as it would pose a high risk of excessive bleeding during thrombolytic treatment.