Bleeding disorders Flashcards
Treatment for Von Willebrand disease (mild)
Minor bleeding due to VWD can be treated with desmopressin (DDAVP), which is a form of vasopressin that increases the release of stored vWF and factor VIII from platelets
what is Von Willebrand disease?
Patients with VWD have either defective or decreased von Willebrand factor (vWF), which binds platelets to subendothelial structures and other platelets at sites of endothelial injury and also acts as a carrier for clotting factor VIII. DDAVP can be used in patients with minor bleeding but generally does not produce a sufficient increase in vWF and factor-VIII activity to be effective for major bleeding. Patients who have VWD and major bleeding should be treated instead with vWF concentrates.
VWD is generally mild and often subclinical, but patients can present with excessive bleeding in the setting of trauma, surgery, obstetric delivery, or dental work. Medications that affect platelets (nonsteroidal anti-inflammatory drugs, aspirin, P2Y12 inhibitors [like clopidogrel]) can also trigger excessive bleeding. Otherwise, patients can present at any age with profuse bleeding from cuts, excessive bruising, bleeding gums, menorrhagia, epistaxis, postpartum bleeding, or gastrointestinal bleeding.
All treatments for VWD?
DDAVP Releases stored vWF and factor VIII Minor bleeding, prior to minor procedures
vWF concentrate Exogenous addition of vWF Minor bleeding (if DDAVP is ineffective), major bleeding, prior to major surgery
Factor VIII Exogenous addition of factor VIII Major bleeding, emergent major procedures
Tranexamic acid (TXA) Displaces plasminogen from fibrin to inhibit fibrinolysis Minor or major bleeding, especially of mucosal tissue
Platelet transfusion Increases platelet levels Bleeding with thrombocytopenia or platelet dysfunction
Hemophilia A presents with what bleeding pattern on labs? Inheritance?
Given the general workup includes a prothrombin time (PT) and partial thromboplastin time (PTT), it would become obvious quite quickly that the patient’s PTT is prolonged. In a young male with no family history of bleeding disorders and a prolonged PTT, there should be concern for hemophilia A.
Hemophilia A is the most common hemophilia and is inherited in an X-linked recessive fashion. Therefore, its clinical effects are seen primarily in males. The underlying pathogenesis is secondary to a decrease in the amount or the activity of factor VIII. Factor VIII is a cofactor for factor IXa. Because factor VIII is only involved in the intrinsic pathway of the coagulation cascade, only the PTT will be increased. The intrinsic pathway involves factors XII, XI, X, IX, VIII, V, II, and I. Therefore, hemophilia B (factor IX deficiency) will also show an increased PTT in the context of a normal PT and bleeding time.
Multiple inherited or acquired bleeding diatheses occur and are frequently encountered clinically or academically. Although not all coagulation studies are performed in practice, characteristics are useful for determining cause, treatment, and prognosis. In the table below, common clinical manifestations and findings encountered through coagulation studies are summarized. Pathogenesis and treatment can be reviewed by following the references and links provided.
Lab finding for Von Willebrand disease?
Most patients will undergo platelet count testing and coagulation studies during the initial evaluation for excessive bleeding or bruising. Patients with von Willebrand disease (vWD) generally have a normal platelet count, with the exception of those with type 2B vWD, most of whom will have mild thrombocytopenia (eg, platelet count 100,000 to 140,000/µL). Patients with vWD have a normal prothrombin time, but the activated partial thromboplastin time (PTT) may be normal or prolonged, depending on the degree of reduction of the factor VIII level. In this question, abnormal ristocetin assay levels should help assist in making the correct diagnosis.
Laboratory testing in VWD patients reveals a normal platelet count, normal PT, normal or slightly prolonged PTT, and a prolonged bleeding time.
Hemophilia A labs?
The following coagulation profile is consistent with the diagnosis of hemophilia A: Normal platelet count, normal PT, increased PTT.
