Anticoagulation and Antiplatelet Drugs Quiz

Study Notes

Bleeding Disorders

Below 50,000 platelets/cubic mm leads to excessive bleeding after minor trauma, with symptoms such as skin and mucosal purpura.
20,000 platelets/cubic mm can lead to spontaneous bleeding.
Bleeding time (BT) is used to screen for disorders of platelet dysfunction and thrombocytopenia.

Coagulation Tests

Thrombin time (TT): thrombin is added to a patient's blood sample to convert fibrinogen into insoluble fibrin, which makes up the essential clot.
Normal TT is 9-13 seconds; 16-18 seconds is considered prolonged, usually caused by excessive plasmin and/or fibrin-split products.

Disorders of the Common Pathway

Prolonged aPTT and PT indicates a common pathway factor deficiency.
Congenital deficiency of factor V, X, prothrombin, and fibrinogen are rare, while acquired deficiency is indicated by conditions such as vitamin K deficiency and liver diseases.

Medical Management

Vascular defects: hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease) is an autosomal dominant disorder characterized by telangiectasia lesions involving the skin and mucous membranes, leading to bleeding due to inert mechanical fragility of the vessels.

Hereditary Disorders of Connective Tissue

Ehlers-Danlos syndrome, osteogenesis imperfecta, and Marfan syndrome are characterized by abnormal vessel wall weakness, leading to bleeding.

Acquired Connective Tissue Disorders

Scurvy (vitamin C deficiency) causes capillary fragility and delayed wound healing.
Long-term steroid therapy can lead to thinning of connective tissue, resulting in bleeding.
Serum sickness can lead to purpura through immune complex deposits in vessel walls.

Platelet Disorders

Von Willebrand disease is the most common disorder, caused by an autosomal dominant trait, leading to mild to moderate bleeding due to a defect in platelet adhesion.
vWF factor is necessary for carrying factor VIII and allowing platelet adhesion to tissue.

Laboratory Investigation and Treatment

PT and TT are normal in von Willebrand disease.
PFA-100 and aPTT are prolonged, while platelet count is normal.
Immunoassay of vWF and specific assays for factor VIII are necessary to establish the diagnosis and type of vWD.
Treatment involves cryoprecipitate, and PT is used to monitor warfarin therapy.

Anti-Platelet Drugs and Dental Management

Anti-platelet treatment reduces overall mortality from vascular complications by 30%.
Aspirin and nonsteroidal anti-inflammatory drugs (such as ibuprofen) inhibit platelet function.
Detection of bleeding disorders involves a thorough history, clinical examination, and laboratory tests such as PT, aPTT, TT, and platelet count.

Description

Test your knowledge on anticoagulation therapy and antiplatelet drugs with this quiz. Learn about the use of PT and INR in monitoring warfarin therapy, the role of antiplatelet drugs in reducing vascular complications, and the mechanisms of action of aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs).