How to Read and Use Platelet Function Test Reports?
In recent years, with breakthroughs in new platelet function testing technologies and the success of multiple clinical application trials, these new technologies have been playing an important role in achieving precise prevention and treatment of thrombotic diseases and effectively reducing their harm. The clinical application of new platelet function testing technologies is rapidly becoming widespread, emerging as a routine testing item. To help clinical medical staff correctly interpret and rationally apply platelet function test reports in guiding clinical work, we have summarized our experience in the proper application of platelet function testing for reference.
Since platelets have various types of receptors on their surface, activation of any type of platelet receptor can trigger platelet-mediated thrombosis. Moreover, different antiplatelet drugs affect platelet function by blocking different platelet receptor pathways. Therefore, in clinical practice, patients' platelet function should be evaluated based on the functional status of multiple platelet receptors. Platelet function testing for patients should include at least two items: AA (arachidonic acid) and ADP (adenosine diphosphate). Testing only one receptor cannot fully and truly reflect the overall platelet function.
Platelets are extremely susceptible to in vitro factors that may activate their function. Therefore, samples used for platelet function testing must be collected and handled strictly in accordance with regulations. When reading a platelet function test report, one should not only look at the Maximum Aggregation Rate (MAR%) or other platelet function indicators but also pay attention to synchronously tested indicators such as the original platelet count (PLT-0) and original mean platelet volume (MPV-0) of the sample. The closer these results are to the true values of the patient's sample, the more reliable the MAR% in the report is in reflecting the platelet aggregation function of the sample. Conversely, it may indicate that the sample has undergone activation or aggregation before testing, in which case the platelet function level provided in the report is likely not the true status of the patient's platelets. Thus, when reading the report, indicators like the original platelet count and mean volume are crucial for accurately judging the true platelet function and must not be ignored.
The target level of platelet function control should vary for different populations
For individuals at high thrombotic risk, such as patients after coronary PCI (percutaneous coronary intervention) or during treatment for ischemic stroke, the AA and ADP function levels are best controlled at approximately ≤35%. For patients at low thrombotic risk or those with both thrombotic and bleeding risks, the platelet function level can be appropriately increased.
A single test cannot predict a patient's long-term platelet function status
Since the lifespan of platelets is about 7–14 days, and various factors can alter platelet function in vivo, it is recommended that patients at high thrombotic risk or those on long-term antiplatelet therapy undergo platelet function rechecks every three months to ensure the safety and effectiveness of medication. After adjusting medication, retesting should generally be done 3–7 days later; in emergency situations, testing can be performed 24 hours after medication, or the timing can be determined according to the drug instructions.
Since blood thrombosis and hemostatic functions are jointly composed of platelets and coagulation factors, coagulation function indicators should be tested simultaneously when evaluating platelet function.
Pay attention to the patient's medication status before and after testing, and effectively manage their platelet function level
Many drugs, as well as Chinese herbal medicines and health supplements (such as Panax notoginseng, ginseng, Salvia miltiorrhiza, and Ginkgo biloba), can affect platelet function. Therefore, during testing, it is important to understand the patient's medication habits or plans, inform them about drugs and supplements that may influence platelet function, and explain the importance of maintaining consistent medication (including supplements) habits before and after testing.
Choose accurate and stable platelet function testing methods and equipment. Currently, there are various platelet function testing devices and methods based on different principles. Selecting instrument methods confirmed reliable through clinical practice is an important prerequisite for accurate platelet function testing.
By applying platelet function testing technology in accordance with the above recommendations, clinical thrombosis prevention and treatment can be effectively guided, the level of prevention and treatment can be improved, and common past errors can be avoided.
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