Congenital and acquired cases of defective platelet function

on 9.2.09 with 0 comments

  • Congenital

    • Bernard-Soulier syndrome

      • AR deficiency of a platelet membrane glycoprotein that’s required for vWF-mediated platelet adhesion to collagen (the membrane protein is Ib-IX)

      • Associated with the presence of “giant” platelets and a mild thrombocytopenia with a disproportionate bleeding tendency

    • Glanzmann’s thrombasthenia

      • AR deficiency of membrane glycoprotein IIb-IIIa, which is required for platelet aggregation by binding to fibrinogen

      • There may e a severe bleeding tendency

    • Storage pool diseases

      • Normal initial aggregation with collagen or ADP cannot be maintained due to abnormalities of the release reaction

      • Platelet dense granules have decreased levels of ADP, ATP, prostaglandins, and serotonin

      • Examples: Hermansky-Pudlak, Chediak-Higashi, thrombocytopenia with absent radii (TAR syndrome), and Wiskott-Aldrich

    • Grey platelet syndrome

      • Alpha granules are deficient (a-SPD)

      • Variable thrombocytopenia and platelets look gray

  • Acquired

    • Aspirin and other NSAIDS

      • Inhibit COX and thus synthesis of the platelet prostaglandins prostacyclin and thromboxane, which are involved with platelet aggregation and the subsequent release reaction

      • It’s a permanent inhibition, so bleeding time may be prolonged for up to 2 weeks post ingestion

      • Platelet dysfunction may be reversed with a transfusion of small numbers of platelets or with DDAVP

    • Uremia

      • Not really well understood why this causes problems

      • This may also be treated with DDAVP, but correction of underlying kidney d/o is very important

    • Acquired storage pool defect – seen in chronic liver disease

Category: Medical Subject Notes , Pathology Notes



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