From the Guidelines
A prolonged PFA indicates impaired platelet function or activity, suggesting that platelets are not functioning properly to form clots, which can increase the risk of bleeding and may require adjustments in medications, additional testing, or treatment of underlying disorders. This test measures how well platelets form clots, and prolonged closure times suggest that platelets aren't functioning properly. Normal PFA closure times are typically 60-100 seconds for collagen/epinephrine and 60-90 seconds for collagen/ADP cartridges, with prolonged times exceeding these ranges. Common causes include medication effects (especially aspirin, NSAIDs, and antiplatelet drugs), von Willebrand disease, platelet disorders, uremia from kidney disease, and severe anemia, as noted in studies such as 1.
The PFA works by measuring how quickly platelets adhere to a membrane coated with collagen and either epinephrine or ADP under high shear conditions, mimicking blood flow in small vessels. This provides valuable information about primary hemostasis, which is the initial phase of clot formation that depends on proper platelet function. According to recent studies like 1, the PFA-200 can be used to monitor hemostatic effects in patients with acquired von Willebrand syndrome.
Some key points to consider:
- The PFA is sensitive to anemia and thrombocytopenia, as mentioned in 1.
- The test can be influenced by various factors, including medications, hematocrit, platelet count, and the presence of underlying bleeding disorders.
- If you have a prolonged PFA, your doctor may need to adjust medications before procedures with bleeding risk, perform additional testing to identify underlying disorders, or treat the root cause of platelet dysfunction, as suggested by studies such as 1.
Overall, a prolonged PFA is a significant finding that requires careful evaluation and management to prevent bleeding complications, as emphasized by the need for accurate diagnosis and treatment in studies like 1.
From the Research
Prolonged PFA Meaning
A prolonged PFA (Platelet Function Analyzer) closure time indicates a potential issue with platelet function, which can be related to various conditions. The PFA-100 is a test used to assess platelet function by measuring the time it takes for platelets to occlude a capillary tube coated with collagen and epinephrine or collagen and ADP 2.
Possible Causes
Some possible causes of a prolonged PFA closure time include:
- Von Willebrand disease (VWD) 2
- Hemophilia 2
- Clinical thrombocytopenia 2
- Recent aspirin consumption 2
- Shear-dependent platelet function defect 3
- Low-normal VWF and low-normal platelet aggregation 3
Interpretation
It is essential to note that a prolonged PFA closure time is not specific to any particular condition and can be caused by various factors. Therefore, any abnormal PFA-100 result should be thoroughly evaluated by follow-up specific testing to establish the true clinical disorder affecting the individual under investigation 2.
Related Tests
Other tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), can also be used to investigate coagulation disorders. Mixing studies can help differentiate between factor deficiencies and inhibitors, which can guide further diagnostic testing or treatment decisions 4.