Hemostasis Defects (complete) Flashcards Preview

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Flashcards in Hemostasis Defects (complete) Deck (27):
1

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

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

2

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

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

3

What is PT/INR? What is it testing?

- 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)

4

What is APTT? What is it testing?

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

5

What is TT? What is it testing?

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

6

What is bleeding time? What is it testing?

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

7

What is PFA? What is it testing?

- New device => perform in vitro bleeding time
- Can also determine platelet response to agonists

8

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

Prolong PT:
- Vit K deficiency
- Warfarin therapy
- Liver Disease
- Factor 2, 7, 5, 10 deficiencies
- Fibrinogen deficiency

9

What is a differential diagnosis for an abnormal APTT?

Prolonged APTT:
- Hemophilia

10

What is a differential diagnosis for an abnormal TT?

Prolonged TT:
- Heparin contamination
- Fibrinogen deficiency
- Abnormal fibrinogen

11

What is a differential diagnosis for an abnormal bleeding time?

Prolonged BT:
- Thrombocytopenia
- von Willebrand disease
- abnormalities in platelet function

12

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

PFA-100: determines platelet response to agonists

13

Describe the clinical features for hemophilia A&B

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

14

Describe the molecular basis for hemophilia A&B

- X-linked deficiency of Factor 8 (A) or Factor 9 (B)
- Affects males, females = carriers

15

Describe the clinical features for factor 7 deficiency

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

16

Describe the molecular basis for factor 7 deficiency

- AR genetics
- Severe = homozygous
- underproduction of Factor 7

17

Describe the clinical features for von Willebrand disease

Primary hemostasis problems: bleeding in mucosa, under skin

- Prolonged BT
- Prolonged PTT

18

Describe the molecular basis for von Willebrand disease

- Platelets can't adhere to exposed collagen/subendo
- Also deficiency in Factor 8 (vWF normally carries this guy)
- AD genetics

19

Describe the role of liver disease in coagulopathy

Liver produces almost all coag factors

Liver disease => deficiencies in those factors

Prolonged PT, PTT, TT

20

Describe disseminated intravascular coagulation (DIC)

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

21

Explain diagnostic testing for DIC

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

Overall: TREAT THE UNDERLYING CONDITION

22

What is a lupus anticoagulant?

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

23

How does a lupus anticoagulant affect coagulation?

- Although there is a prolonged PTT, there is no bleeding problem
- Actually causes thrombosis!!

24

How can one test for a lupus anticoagulant?

- dilute Russell's Viper Venom Test (dRVVT) => directly activates factor 10
- Reveals a prolonged clotting time w/ dRVVT

25

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

- 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

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

- The pt's plasma now has the clotting factor present from donor plasma
- Will normalize PTT

27

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

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