Bleeding, Thromotic, and Fibrinolytic Disorders Flashcards
What are the two main functions of von Willebrand factor?
Binds platelets to form the initial platelet plug. Binds with Factor VIII to prolong it’s half life
What is the most common inherited bleeding disorder?
von Willebrand, autosomal dominant
Describe the different types of von Willebrand disease
Type 1-Quantitative abnormality of vWF, most common. Type 2-Qualitative abnormality, Decreased binding to factor VIII and platelets, resembles hemophilia A. Type 3 -Rare, Undetectable levels of vWF and severe bleeding in infancy and childhood
What are symptoms of von Willebrand disease?
Nosebleeds > 10 min in childhood. Lifelong easy bruising (associated hematoma). Bleeding following dental extractions or other surgery. Heavy menstrual bleeding or post partum
What laboratory tests should be done for von Willebrand disease?
Plasma vWF antigen, Plasma vWF activity (vWF:Rco and vWF collagen), Factor VIII activity. PT normal. PTT normal or prolonged depending on the Factor VIII activity
What are treatment options for von Willebrand disease?
DDAVP (minor bleeding), vWF concentrate (major bleeding or for type 2 and 3). Avoid aspirin/NSAIDs
What is the pathophysiology behind disseminated intravascular coagulation?
Massive release of tissue factor. Tissue factor sets the coagulation system in place. Coagulation occurs. Clotting factors and inhibitors are consumed. Clots further trap circulating platelets leading to ischemia
What happens as a result of excess thrombin in DIC?
activates plasmin resulting in fibrinolysis. This breakdown of clots = fibrin degradation products which have further anticoagulant properties. Plasmin also activates the complement and kinin systems = shock
What are common causes of DIC?
massive tissue injury, obstetric complications, sepsis, snake bite, cancer
What lab results are associated with DIC?
Thrombocytopenia. Prolongation of PT and PTT. Low fibrinogen. Increased levels of fibrinogen degradation products (d-Dimer). Schistocytes (helmet cells)
What are treatment options for DIC?
Anticoagulants only to prevent imminent death. Platelets or coagulation factor replacement in the case of plts < 50K and serious bleeding. Fresh frozen plasma or cryoprecipitate to keep fibrinogen > 100 mg/dL if significantly elevated PT/INR
What is the pathophysiology behind hypercoagulable states?
endothelial damage and inflammation, elevated platelet levels
What conditions accelerate the activity of the clotting system?
Pregnancy. Oral contraceptives. Postsurgical state. Malignancy (renal cell carcinoma). Hereditary clotting disorders
What are risk factors for abnormal clotting?
Stasis/Immobility (DVT). Low cardiac output (CHF). Obesity. Sleep apnea
What are the hereditary clotting disorders?
Protein C, Protein S, Antithrombin III, Factor V Leiden, Antiphospholipid antibody
What is the fxn of protein C?
inactivates Factors V and VIII thereby inhibiting anticoagulation. A deficiency of Protein C leads to prolonged action of Factors V and VIII leading to excessive clotting
What are symptoms of protein C deficiency?
Thrombosis, Deep vein thrombosis, Pulmonary embolism, Thrombophlebitis
How should you work up a suspected protein C deficiency?
Protein C, PTT, PT, Thrombin time, Bleeding time,
Medical and family history
What are treatment options for protein C deficiency, protein S deficiency, antithrombin III deficiency, factor V Leiden?
Treat with anticoagulants if at high risk for clotting such as surgery or hospitalization. Chronic anticoagulation if history of thrombosis
What is the fxn of protein S?
needed for proper function of Protein C. A deficiency in Protein S results in diminished ability of Protein C to inactivate Factors V and VIII resulting in excessive clotting