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B&L Unit 3 > Hemostasis Defects (complete) > Flashcards

Hemostasis Defects (complete) Flashcards

1
Q

What are the major congenital disease states causing bleeding and/or clotting?

A

1) Hemophilia A (F8)
2) Hemophilia B (F9)
3) Hemophilia C (F11)
4) von Willebrand Disease
5) Factor VII deficiency

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2
Q

What are the major acquired disease states causing bleeding and/or clotting?

A

1) Liver disease
2) Vit K deficiency/Warfarin administration
3) Disseminated Intravascular Coagulation (DIC)

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3
Q

What is PT/INR? What is it testing?

A
  • Prothrombin time (PT), international normalized ratio (INR)
  • Measures extrinsic and common pathway
  • Sensitive to Warfarin

PT: Time to clot in seconds (nl: 9-12)

INR: 1 is normal, 2 is twice normal (this is a standardized measurement b/c each test manufacturer is different)

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4
Q

What is APTT? What is it testing?

A
  • Measures intrinsic and common pathways
  • Sensitive to inhibition by heparin and fibrin split products
  • Nl: 25-32 seconds
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5
Q

What is TT? What is it testing?

A
  • Measures procoagulant activity of fibrinogen
  • Sensitive to inhibition by heparin and fibrin split products
  • Nl: 12-18 seconds
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6
Q

What is bleeding time? What is it testing?

A
  • Measures platelet and vessel interaction
  • Standardized cut + simplate bleeding time device on forearm => time to clot is measured
  • Nl: 2-9 minutes
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7
Q

What is PFA? What is it testing?

A
  • New device => perform in vitro bleeding time

- Can also determine platelet response to agonists

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8
Q

What is a differential diagnosis for an abnormal PT/INR?

A

Prolong PT:

  • Vit K deficiency
  • Warfarin therapy
  • Liver Disease
  • Factor 2, 7, 5, 10 deficiencies
  • Fibrinogen deficiency
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9
Q

What is a differential diagnosis for an abnormal APTT?

A

Prolonged APTT:

- Hemophilia

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10
Q

What is a differential diagnosis for an abnormal TT?

A

Prolonged TT:

  • Heparin contamination
  • Fibrinogen deficiency
  • Abnormal fibrinogen
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11
Q

What is a differential diagnosis for an abnormal bleeding time?

A

Prolonged BT:

  • Thrombocytopenia
  • von Willebrand disease
  • abnormalities in platelet function
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12
Q

What are some other tests used to evaluate patients w/ thrombotic or bleeding disorders?

A

PFA-100: determines platelet response to agonists

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13
Q

Describe the clinical features for hemophilia A&B

A
  • Unexplained hematomas, bruises, post-surgical or traumatic bleeding
  • Joint bleeding => joint fusion/destructive arthritis
  • CNS bleeds (COD usually)
  • Retroperitoneal/psoas bleeds
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14
Q

Describe the molecular basis for hemophilia A&B

A
  • X-linked deficiency of Factor 8 (A) or Factor 9 (B)

- Affects males, females = carriers

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15
Q

Describe the clinical features for factor 7 deficiency

A
  • Severe bleeding disorder similar to hemophilia (joints, muscles, soft tissue, retroperitoneal space, CNS)
  • Prolonged PT
  • Normal PTT
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16
Q

Describe the molecular basis for factor 7 deficiency

A
  • AR genetics
  • Severe = homozygous
  • underproduction of Factor 7
17
Q

Describe the clinical features for von Willebrand disease

A

Primary hemostasis problems: bleeding in mucosa, under skin

  • Prolonged BT
  • Prolonged PTT
18
Q

Describe the molecular basis for von Willebrand disease

A
  • Platelets can’t adhere to exposed collagen/subendo
  • Also deficiency in Factor 8 (vWF normally carries this guy)
  • AD genetics
19
Q

Describe the role of liver disease in coagulopathy

A

Liver produces almost all coag factors

Liver disease => deficiencies in those factors

Prolonged PT, PTT, TT

20
Q

Describe disseminated intravascular coagulation (DIC)

A
  • Systemic activation of coagulation => intravascular fibrin deposition & depletion of platelets and coag factors
  • Fibrin dep => thrombosis and organ failure
  • Depletion => bleeding
21
Q

Explain diagnostic testing for DIC

A
  • Low fibrinogen level
  • Low platelet count
  • Increased D-dimers
  • Prolonged PTT
  • Prolonged TT

Overall: TREAT THE UNDERLYING CONDITION

22
Q

What is a lupus anticoagulant?

A
  • IgG Ab => reacts against phospholipid in platelet membrane or endo cell
  • causes Antiphospholipid Antibody Syndrome (APS)
23
Q

How does a lupus anticoagulant affect coagulation?

A
  • Although there is a prolonged PTT, there is no bleeding problem
  • Actually causes thrombosis!!
24
Q

How can one test for a lupus anticoagulant?

A
  • dilute Russell’s Viper Venom Test (dRVVT) => directly activates factor 10
  • Reveals a prolonged clotting time w/ dRVVT
25
Q

Explain how a 1:1 mixing study can distinguish a clotting factor deficiency from an inhibitor of coagulation

A
  • Patient’s plasma and normal plasma mixed together
  • clotting factor deficiency => will return to normal PTT
  • coag inhibitor (like an Ab against a factor) => unchanged
26
Q

Why does the PTT change to normal during a 1:1 mixing study for clotting factor deficiency?

A
  • The pt’s plasma now has the clotting factor present from donor plasma
  • Will normalize PTT
27
Q

Why does the PTT remain unchanged during a 1:1 mixing study for a coagulation inhibitor?

A
  • The Ab continues to targets the specific factor
  • Donor plasma just gives more factor for Ab to target
  • No change to PTT

B&L Unit 3 (12 decks)

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