Coag 2.3 Coagulation System Disorders Flashcards
- The APTT is sensitive to a deficiency of which clotting factor?
A. Factor VII
B. Factor X
C. PF3
D. Calcium
B. Factor X
- Which test result would be normal in a patient with dysfibrinogenemia?
A. TT
B. APTT
C. PT
D. Immunologic fibrinogen level
D. Immunologic fibrinogen level
The level of plasma fibrinogen determined immunologically is normal. In a patient with dysfibrinogenemia, fibrinogen is not polymerized properly, causing abnormal results of the fibrinogen-dependent coagulation tests.
- A patient with a prolonged PT is given intravenous vitamin K. PT is corrected to normal after 24 hours. Which clinical condition most likely caused these results?
A. Necrotic liver disease
B. Factor X deficiency
C. Fibrinogen deficiency
D. Obstructive jaundice
D. Obstructive jaundice
Obstructive jaundice contributes to coagulation disorders by preventing vitamin K absorption. Vitamin K is fat soluble and requires bile salts for absorption. Parenteral administration of vitamin K bypasses the bowel, hence the need for bile salts.
- Which factor deficiency is associated with prolonged PT and APTT?
A. Factor X
B. Factor VIII
C. Factor IX
D. Factor XI
A. Factor X
- Prolonged APTT is corrected with factor VIII–deficient plasma but not with factor IX–deficient plasma. Which factor is deficient?
A. Factor V
B. Factor VIII
C. Factor IX
D. Factor X
C. Factor IX
- Which of the following is a characteristic of classic hemophilia A?
A. Abnormal PLT aggregation
B. Autosomal recessive inheritance
C. Mild to severe bleeding episodes
D. Prolonged PT
C. Mild to severe bleeding episodes
Hemophilia A (factor VIII deficiency) is characterized by mild to severe bleeding episodes, depending on the concentration of factor VIII:C. Hemophilia A is inherited as a sex-linked disease. PLT aggregation and PT are both normal in hemophilia A.
- Refer to the following results:
PT = prolonged
APTT = prolonged
PLT count = decreased
Which disorder may be indicated?
A. Factor VIII deficiency
B. von Willebrand disease
C. DIC
D. Factor IX deficiency
C. DIC
In DIC, there is a diffuse intravascular generation of thrombin and fibrin. As a result, clotting factors and PLTs are consumed, resulting in decreased PLT count and increased PT and APTT.
- Which of the following is a predisposing condition for the development of DIC?
A. Adenocarcinoma
B. Idiopathic thrombocytopenic purpura (ITP)
C. Post transfusion purpura (PTP)
D. Heparin-induced thrombocytopenia (HIT)
A. Adenocarcinoma
Adenocarcinoma can liberate procoagulant (thromboplastic) substances that can activate prothrombin intravascularly. ITP is a thrombocytopenia caused by an autoantibody; PTP is an alloimmune thrombocytopenia caused by transfusion of blood or blood products; HIT results from an antibody to heparin–PF4 complex causing thrombocytopenia in 1% to 5% of patients who are on heparin therapy. In some affected persons, thrombosis may also occur.
- Factor XII deficiency is associated with:
A. Bleeding episodes
B. Epistaxis
C. Decreased risk of thrombosis
D. Increased risk of thrombosis
D. Increased risk of thrombosis
Factor XII–deficient patients commonly have thrombotic episodes. In vitro, activated factor XII (XIIa) activates factor XI to factor XIa. In vivo, however, factor XII plays a major role in the fibrinolytic system by activating plasminogen to form plasmin. Hemorrhagic manifestations are not associated with factor XII deficiency because VIIa/TF can activate factor IX to factor IXa and factor X to factor Xa to generate thrombin
- The following results were obtained on a patient: normal PLT count and function, normal PT, and prolonged APTT. Which of the following disorders is most consistent with these results?
A. Hemophilia A
B. Bernard–Soulier syndrome
C. von Willebrand disease
D. Glanzmann thrombasthenia
A. Hemophilia A
Hemophilia A is associated with deficiency of factor VIII, resulting in bleeding and abnormal APTT. The PLT number and function are normal in this disorder. Von Willebrand disease is a disorder of PLT adhesion associated with decreased VWF and factor VIII, causing an abnormal PLT function test result and abnormal APTT. Both Glanzmann thrombasthenia and Bernard–Soulier syndrome cause abnormal PLT aggregation but do not cause abnormal APTT.
- The following laboratory results were obtained from a 40-year-old woman:
PT = 20 sec
APTT = 50 sec
TT = 18 sec
What is the most probable diagnosis?
A. Factor VII deficiency
B. Factor VIII deficiency
C. Factor X deficiency
D. Hypofibrinogenemia
D. Hypofibrinogenemia
Fibrinogen (factor I) is a clotting protein of the common pathway and is evaluated by TT. In hypofibrinogenemia (fibrinogen concentration less than 100 mg/dL), PT, APTT, and TT are prolonged. In factor VII deficiency, APTT is normal; in factor VIII deficiency, PT is normal; and in factor X deficiency, TT is normal.
- When performing a factor VIII activity assay, a patient’s plasma is mixed with:
A. Normal patient plasma
B. Factor VIII–deficient plasma
C. Plasma with a high concentration of factor VIII
D. Normal control plasma
B. Factor VIII–deficient plasma
- The most suitable product for treatment of factor VIII deficiency is:
A. Fresh frozen plasma (FFP)
B. Factor VIII concentrate
C. Prothrombin complex concentrate
D. Factor V Leiden
B. Factor VIII concentrate
Factor VIII concentrate (human or recombinant) is the treatment of choice for patients with factor VIII deficiency. FFP contains factor VIII; however, it is no longer used as the primary treatment for factor VIII deficiency. Prothrombin complex concentrate is used to treat patients with factor VIII inhibitor.
- Which of the following is associated with an abnormal PLT aggregation test result?
A. Factor VIII deficiency
B. Factor VIII inhibitor
C. Lupus anticoagulant
D. Afibrinogenemia
D. Afibrinogenemia
- Refer to the following results:
PT = normal
APTT = prolonged
PLT count = normal
PLT aggregation to ristocetin = abnormal
Which of the following disorders may be indicated?
A. Factor VIII deficiency
B. DIC
C. von Willebrand disease
D. Factor IX deficiency
C. von Willebrand disease
VWF is involved in both PLT adhesion and coagulation via complexing with factor VIII. Therefore, in von Willebrand disease (deficiency or functional abnormality of VWF) factor VIII is also decreased, causing abnormal APTT as well as abnormal PLT aggregation to ristocetin. The PLT count and PT are not affected in VWF deficiency.
- Which results are associated with hemophilia A?
A. Prolonged APTT, normal PT
B. Prolonged PT and APTT
C. Prolonged PT, normal APTT
D. Normal PT and APTT
A. Prolonged APTT, normal PT
Hemophilia A is associated with factor VIII deficiency. Factor VIII is a factor in the intrinsic coagulation pathway that is evaluated by the APTT test and not the PT test. The PT test evaluates the extrinsic and common pathways.
- Fibrin monomers are increased in which of the following conditions?
A. Primary fibrinolysis
B. DIC
C. Factor VIII deficiency
D. Fibrinogen deficiency
B. DIC
Increased fibrin monomers result from coagulation activation. DIC is an acquired condition associated with spontaneous activation of coagulation and fibrinolysis. In primary fibrinolysis, the fibrinolytic system is activated, and fibrin monomers are normal.
- Which of the following is associated with multiple factor deficiencies?
A. An inherited disorder of coagulation
B. Severe liver disease
C. Dysfibrinogenemia
D. Lupus anticoagulant
B. Severe liver disease
Most of the clotting factors are made in the liver. Therefore, severe liver disease results in multiple-factor deficiencies. An inherited disorder of coagulation is commonly associated with a single-factor deficiency. Lupus anticoagulant is directed against the phospholipid-dependent coagulation factors. Dysfibrinogenemia results from an abnormal fibrinogen molecule.
- Normal PT and APTT results in a patient with poor wound healing may be associated with:
A. Factor VII deficiency
B. Factor VIII deficiency
C. Factor XII deficiency
D. Factor XIII deficiency
D. Factor XIII deficiency
- Fletcher factor (prekallikrein) deficiency may be associated with:
A. Bleeding
B. Thrombosis
C. Thrombocytopenia
D. Thrombocytosis
B. Thrombosis
Fletcher factor (prekallikrein) is referred to as a contact factor. Activated prekallikrein is named kallikrein. In vitro, kallikrein is involved in activation of factor XI to XIa causing prolonged APTT. In vivo, it plays a role in the fibrinolytic system and, similar to factor XII deficiency, Fletcher factor deficiency may be associated with thrombosis.
- One of the complications associated with a severe hemophilia A is:
A. Hemarthrosis
B. Mucous membrane bleeding
C. Mild bleeding during surgery
D. Immune-mediated thrombocytopenia
A. Hemarthrosis
In severe hemophilia A, factor VIII activity is less than 1%, resulting in a severe bleeding diathesis, such as hemarthrosis (bleeding into the joints).
- The most common subtype of classic von Willebrand disease is:
A. Type 1
B. Type 2A
C. Type 2B
D. Type 3
A. Type 1
- Prolonged APTT and PT are corrected when mixed with normal plasma. Which factor is most likely deficient?
A. Factor VIII
B. Factor V
C. Factor XI
D. Factor IX
B. Factor V
