MHD: Abnormal Hemostasis Flashcards
What are the two general categories of platelet disorders?
Quantitative
Qualitative
What is thrombocytopenia?
Decreased platelet count leading to bleeding
What is thrombocytosis?
A benign increase in platelet count
Can cause bleeding or thrombosis
What is thrombocythemia?
A neoplastic clonal proliferation of platelets
Can cause bleeding or thrombosis
What can cause thrombocytopenia?
Bone marrow alterations (cancer) Hereditary defects Abnormal hematopoiesis (folate deficiency) Drugs (heparin, sulfonamides ...etc.) Dilutional (dialysis)
How does heparin induced thrombocytopenia occur?
Complexes of Heparin and PF4 form
Autoantibodies lead to destruction of platelets leading to thrombosis
What are the two categories of thrombocytopenic purpura?
Immune thrombocytic purpura (ITP)
Thrombotic thrombocytic purpura (TTP)
What role does the spleen play in ITP?
The splenic plasma cells produce IgG against platelet antigens
Splenic macrophages digest antibody bound platelets.
Cure for ITP: splenectomy
What are the causes of thrombocytosis?
Splenectomy
Reactive thrombocytosis (cancer, infection, or drug induced)
Autonomous thrombocytosis
What are the three inducers of qualitative platelet disorders?
Disease (liver disorders)
Drugs (aspirin, NSAIDS)
Diet (omega 3 fatty acids)
What are the inherited qualitative platelet disorders?
Glanzmann’s thrombasthemia (GPIIb/IIIa defect)
Bernard-Soulier disease (GPIb defect)
What is non-thrombocytopenic purpura?
Vascular disorders leading to easy bruising, bleeding, purpura, vasculitis with normal platelet function and coagulation
What is the most common congenital endothelial disorder?
Hereditary hemorrhagic telangiectasia (HHT)
What is the main nutritional disorder that can cause bleeding?
Scurvy, vitamin C deficiency
What are the two coagulation defects associated with the intrinsic pathway?
Hemophilia A (VIII) Hemophilia B (IX)
What type of inheritance do the hemophilias have?
Sex linked recessive
What is the most common inherited coagulation disorder?
Von willebrand disease: genetic vWF deficiency
What lab tests can distinguish hemophilia from VWD?
In hemophilias, bleeding time is unchanged whereas bleeding time is elevated in VWD
Describe primary fibrinolysis
Excessive fibrinolysis leads to bleeding because fibrinogen levels are decreased
What is another name for secondary fibrinolysis?
Disseminated intravascular coagulation (DIC)
What processes occur during DIC?
DIC is associated with fibrinolysis and coagulation
What is the hallmark test used for DIC?
D-dimer test: looks for fibrin split products
Describe the pathogenesis of sepsis associated DIC
Tissue destruction and sepsis lead to the release of tissue factor, which causes widespread thrombosis.
Thrombosis leads to decreased platelets and activated plasmin (both leading to increased bleeding)
What is the result of α2-antiplasmin deficiency?
Bleeding
Increased fibrinolysis due to an inability to inhibit plasmin
