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Steve IHO week 6 > Krafts Friday Thrombotic Disorder > Flashcards

Krafts Friday Thrombotic Disorder Flashcards

1
Q

Lines of Zahn

A

looking at a blood clot on autopsy. If these lines exist, then the clot happened before death.

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2
Q

Thrombosis Risk Factors

A

Endothelial damage –> atherosclerosis: hypertension, hyperlipidemia, obesity, smoking

Blood Stasis: immobilization, varicose veins, cardiac dysfunction

Hypercoagulability: trauma/surgery, carcinoma, estrogen/postpartum, thrombotic disorders

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3
Q

Your patient has a thrombus……now what?

A

Get a good history: Risk factors, Family history

Order routine lab tests: INR, PTT, TT

Start to worry if: No obvious cause, Family history, Weird location, Recurrent, Patient is young, Miscarriages

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4
Q

Thrombotic Disorders: names of disorders

A 
Hereditary:
*Factor V Leiden*
ATIII deficiency
Protein C deficiency
Protein S deficiency
Factor II gene mutation
Homocysteinemia

Acquired
antiphospholipid Ab

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5
Q

Factor V Leiden: things you must know

A

Most common cause of unexplained thromboses
Point mutation in factor V gene
Factor V can’t be turned off (You can turn it on…but you can’t turn it off!)
Need genetic testing for diagnosis

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6
Q

What is Factor V Leiden?

A

A mutated factor V gene:
Single point mutation
Discovered in Leiden, Netherlands

Produces abnormal factor V:
Participates in the cascade
Can’t be cleaved by protein C

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7
Q

Factor V Leiden: PTT and INR are not helpful! Why?

A

You make the fibrin at the same rate, you just can’t shut it off. Goes no faster and no slower.

Need genetic testing!

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8
Q

What is the risk of getting a clot with Factor V Leiden

A

Heterozygotes: 7 times normal
Homozygotes: 80 times normal
Normal risk = 1-2 patients per 1000 (per year)

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9
Q

How common is factor V Leiden?

A

Half of patients with unexplained thromboses
5% of Caucasians have it
VERY rare in non-Caucasians

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10
Q

How do you treat Factor V Leiden

A

DON’T…unless there is a thrombosis.
Then: give an anticoagulant for a while (Coumadin)

If there are multiple episodes (or other risk factors), give long-term anticoagulation.

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11
Q

Antithrombin III Deficiency: things you must know

A

ATIII is a natural anticoagulant
Potentiated by heparin
Lots of gene mutations exist
Very rare

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12
Q

What is antithrombin III

A

Natural anticoagulant
Inhibits IIa, VIIa, IXa, Xa, XIa
Potentiated by heparin so you can’t give them heparin to help

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13
Q

What’s wrong with the ATIII gene in the ATIII deficiency

A 
Mutated gene produces less ATIII
Rara avis (
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14
Q

What’s the risk of getting a clot with ATIII deficiency

A

Homozygotes: can’t survive.
Heterozygotes: half get clots.
Heparin won’t work (obviously).
Antithrombin concentrates required.

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15
Q

Protein C deficiency and S Deficiencies: things to know

A

Proteins C and S are natural anticoagulants
C is also fibrinolytic and anti-inflammatory
Warfarin-induced skin necrosis
C deficiency rare; S deficiency super-rare

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16
Q

What is protein C

A

Anticoagulant: inactivates Va and VIIIa
Fibrinolytic: promotes t-PA action
Anti-inflammatory: keeps cytokines low

17
Q

What’s wrong with the protein C gene in protein C deficiency

A 
Mutated gene produces less protein C (or defective protein C)
Rara avis (
18
Q

What’s the risk of getting a clot with protein C deficiency

A

Heterozygotes: 7 times normal
Unique risks:
Warfarin-induced skin necrosis
Purpura fulminans

19
Q

what is the first thing coumadin inhibits, why is it important

A

protein C is inhibited first so you actually have an increased change of thrombosis right away, especially if you have a defect

20
Q

Purpura Fulminans

A

Thrombotic state + vascular injury
Net result: skin necrosis
Associated with: protein C and S deficiency, sepsis
Treatment may include administering protein C

21
Q

Protein S Deficiency

A

Über rara avis

Otherwise: same as protein C deficiency

22
Q

Factor II Gene Mutation: things you must know

A

Factor II = prothrombin
Mutated gene makes too much prothrombin
Prothrombin itself is normal
Rare in non-Caucasians

23
Q

What’s wrong with the factor II gene when it is mutated

A

Mutated gene produces too much prothrombin!

Prothrombin itself is normal

5% of caucasians (rare in others)

Clot risk: 2 - 20 times normal

24
Q

Hyperhomocysteinemia: things you must know or you will die

A

Homocysteine converts folate
Homocysteinuria = rare metabolic disorder
Too much homocysteine = thromboses
Homocysteinemia has many causes

25
Q

What is Homocysteine?

A

Amino acid
Made from methionine
Maintains myelin
Converts dietary folate

26
Q

Homocysteinuria

A

Rare metabolic disorder
Deficient trans-sulphuration enzyme
increased homocysteine in blood, urine
increased thrombosis, premature atherosclerosis

27
Q

Homocysteinemia

A

Not so rare
MTHFR gene mutation
B12/folate deficiency

28
Q

What’s so bad about homocysteine?

A

Toxic to endothelium:
Forms reactive oxygen species

Interferes with nitric oxide:
NO is a vasodilater and an antithrombotic

29
Q

Heterozygous homocysteinemia

A

increased thrombosis, premature atherosclerosis
Risk of venous thrombosis: 2.5 x normal
Risk of arterial thrombosis: 10 x normal

30
Q

Homocysteinemia in B12/folate deficiency

A

Less worrisome than heterozygous

…but watch out for other risk factors

31
Q

Antiphospholipid Antibodies: Things you must know

A 
Acquired
Autoantibodies against phospholipids
Falsely prolong INR
May cause thromboses
Antiphospholipid syndrome is serious
32
Q

What are antiphospholipid antibodies?

A 
IgG antibodies against phospholipids
Three variants:
1. anticardiolipin antibodies
2. lupus anticoagulants
3. antibodies against other molecules
33
Q

What do antiphospholipid antibodies do?

A

Bind to phospholipids (in vivo and in vitro)
Screw up coagulation tests: bind up PTT/PT reagent, specimen can’t clot, test result appears prolonged

Screw up other tests: direct antiglobulin test, syphilis test

34
Q

antiphospholipid antibodies do what in vivo an in vitro

A

Promote coagulation in vivo

Inhibit coagulation in vitro

35
Q

Who develops antiphospholipid antibodies

A

Children: Infection, Mild risk

Adults: Autoimmune diseases, Moderate risk

Elderly: Drugs, No risk

36
Q

Antiphospholipid Antibody Syndrome: what happens clinically

A 
Recurrent thrombosis
Recurrent spontaneous abortions
Increased risk of stroke
Pulmonary hypertension 
Renal failure
37
Q

How do you detect the antiphospholipid antibodies

A
  1. Order a PTT.
  2. If prolonged, order a PTT mixing study.
    If the PTT corrects…? then it was a factor problem
    If the PTT doesn’t correct…? there is something inhibitory in the blood
  3. If normal, antibody may still be present! Order fancy tests.

Steve IHO week 6 (3 decks)

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