Platelet disorders and Aggregometry Glanzmann Thrombasthenia • Defective aggregation to all agonists except ristocetin • Normal platelet, PT, PTT (diff from afibrinogenemia, which will have a similar aggregation pattern) • Platelet count and platelet morphology — normal • Platelet flow cytometry — GP Ilb/llla (CD41/CD61) is absent Bernard-SouIier • Defective aggregation to high-dose ristocetin; normal aggregation with other agonists • This pattern could also be seen in vWD (either severe Type 1 or Type 3) — differentiate vWD from BS by measuring vWF level or flow for Gplb receptor • Thrombcytopenia and giant platelets • Platelet flow cytometry— GP lb/lX/V (CD42b) is absent or dysfunctional; may be normal with qualitative defects of GP lb/lX/V Von Willebrand Disease • Decreased aggregation to HD ristocetin, but platelet aggregation is not considered first-line testing • Usually normal platelet count and morphology Dr. Laura Brown @lauraebrown #Platelet #disorders #hematology #hemepath #differential #diagnosis #Aggregometry
