Platelet Function Tests

What are they?
Why are they done?
Common Tests
Sources

Common Platelet Function Tests
Below are some of the tests that are being used to determine platelet function. In the coming years, these testing methods are expected to change and evolve as researchers continue to search for procedures that better describe and evaluate the complex clotting process.

Tests	Used for	Advantages	Disadvantages
Bleeding Time	Screening, largely being phased out in favor of PFA-100 or other methods	Physiological	Not sensitive, subject to operator variability, poor reproducibility, predictive value poor, often scars
Platelet function analyzer (PFA-100®)	Screening, mimics clotting process, evaluates adhesion and aggregation	Rapid, simple screening tool, identifies aspirin ingestion, can screen for von Willebrand and may monitor von Willebrand and anti-platelet therapy	Sensitive to platelet count and hematocrit, full clinical use yet to be established
Platelet Aggregometry	Follow-up to abnormal Bleeding Time or PFA-100, detects responsiveness to panel of platelet activators (collagen, ADP, epinephrine, ristocetin, Arachidonic acid)	Can diagnose inherited and acquired platelet dysfunction, measures aggregation	Labor intensive and relatively slow
Plateletworks®	Platelet counting pre and post activation, monitoring platelet function during cardiopulmonary bypass procedures	Rapid, simple point-of- care test, measures percentage of platelet aggregation in whole blood	Does not measure overall primary hemostasis
VerifyNow® IIb/IIIa Assay	Monitor Gp IIB/IIIa anti-platelet therapy (glycoprotein inhibitors that inhibit the interaction between platelets and fibrin)	Rapid, simple point-of- care test for monitoring anti-Gp IIb/IIIa therapy, measures aggregation	Currently FDA approved for monitoring abciximab Gp IIb/IIIa and eptifibatide therapy
VerifyNow® Aspirin Assay	Detect platelet dysfunction due to aspirin ingestion	Rapid, simple point-of-care test	Current FDA approved only for detecting platelet dysfunction due to aspirin ingestion, qualitative
Flow Cytometry	Measure platelet glycoproteins, activation markers, platelet function and turnover, platelet counting, reticulated platelets	Flexible and powerful, range of tests, can diagnose disorders	Requires specialized operator, expensive equipment, mostly research tool at this point
Thromboelastography (TEG)	Measure clot strength, monitor platelet function and coagulation	Good technique for measuring clot strength in whole blood	Clinical utility/necessity still being argued