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Heme boards > Von Willebrand Syndrome > Flashcards

Von Willebrand Syndrome Flashcards

1
Q

VWS subtypes that are not autosomal dominant

A

Type 2N
Type 3
(autosomal recessive)

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2
Q

von willebrand factor primary functions

A

1) Facilitate platelet binding to subendothelial collagen
2) facilitate platelet-platelet interactions
3) Protect clotting factor VIII

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3
Q

What chromosome is VWF located on?

A

12

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4
Q

What is VWS type 1?

A

mild quantitative, partial deficiency

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5
Q

VWS type 1 lab profile

A

***concurrent reduction of activity (ristoecetin) and antigen (21%-25% still considered concordant)
Low Factor 8 (VWF is a carrier protein)
Low antigen level
Ristocetin low or normal
RIPA low or normal

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6
Q

VWS Type 1c 1) physiology 2) how to determine

A

1) Quantitative decrease in VWF with preserved ratios between VWF antigen, activity, and factor III
*increased clearance (think of letter c) of Von willebrand factor antigen
2) Response to DDAVP - rapid increase and then rapid decrease/clearance

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7
Q

VWS type 3 labs

A
  • Factor VIII very low
  • VWF antigen very low to nonexistent
  • ristocetin very low
  • RIPA very low
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8
Q

VWS type 2A - 1) Factor VIII 2) VWF antigen 3) RIPA 4) multimere assay

A
  • Factor VIII low
  • VWF antigen low
  • ristocetin very low
  • RIPA very low
  • large and intermediate sized multimeres are absent
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9
Q

VWS type 2B labs 1) Factor VIII 2) VWF antigen 3) ristocetin 4) RIPA 5) multimeres

A
  • gain of function, tight bond between platelets and VWF
  • Factor VIII low
  • VWF antigen low
  • ristocetin very low
    ***RIPA high (heightened sensitivity to ristocetin) leading to thrombocytopenia
    *large multimeres absent
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10
Q

Drug contraindicated in type 2B

A

DDAVP (will exacerbate thrombocytopenia)

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11
Q

VWS type 2N physiology

A

Low affinity for factor VIII

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12
Q

VWS type 2N labs 1) Factor VIII 2) VWF antigen 3) ristocetin 4) RIPA

A
  • Factor VIII very low (NO 8, lack of binding to Factor VIII so there’s no Factor VIII in circulation)
  • VWF antigen normal
  • ristocetin normal
  • RIPA normal (measures platelet aggregation with VWF, not Factor VIII)
    **looks like hemophilia A due to low factor VIII, which is common board question, but will be a female (VWS is not x linked)
    -
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13
Q

VWS type 2M - 1) FVIII 2) RIPA 3) multimeres

A
  • FVIII normal or decreasd
  • RIPA decreased
  • *normal multimeres
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13
Q

DDAVP SE’s

A
  • hypotension
  • flushing
  • hyponatremia and seizures
    *tachyphylaxis
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14
Q

causes of acquired VWS

A
  • lymphoproliferative
  • plasma cell disorders
  • autoimmune
    *hypothyroidism
  • medications
  • aortic stenosis
  • LVADs
  • ECMO
    *wilm’s tumor
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15
Q

Unique aspect of VWS secondary to MGUS

A

Typically responds to IVIG

16
Q

acquired VWS subtype from hypothyroidism

A

Type 1

17
Q

acquired VWS subtype from valvular disorders

A

Type 2

17
Q
A
17
Q

acquired VWS subtype from MPN

A

type 2 VWD

17
Q

VWS type 1 pathophys

A

Partial quantitative deficiency of VWF

18
Q

Type 2 VWS pathophys

A
  • decreased VWF-dependent platelet adhesion without selective deficiency of multimeres
19
Q

Functional assay now recommended by ASH over ristocetin cofactor assay

A

VWF:GPIbM or VWF:GP1bR

20
Q

Confirmed diagnosis on basis of VWF antigen

A

<30% = VWF antigen (even in absence of bleeding)
OR
<50% + bleeding

21
Q

Management of menstrual bleeding in Type 1 patient

A

Type 1 - hormonal therapy (OCP or levonorgestrel IUD) OR TXA starting on first day of menses and continuing for 3-5 days with each cycle

22
Q

Goal VWF activity for neuraxial anesthesia in VWD

A

VWF activity level of ≥0.50 IU/dL is considered adequate for neuraxial anesthesia
IF below, give VWF concentrate (Goal is 0.50-1.50 IU/mL

23
Q

Management of postpartum bleeding in VWD

A

TXA

24
Q

Next step after diagnosing VWD Type 2

A

Send multimere analysis
IF normal, then 2M
IF abnormal it’s 2A or B and you need genetic testing

25
Q

Ratio of VWF activity: VWF:Ag confirming type 2 VWD

A

<0.7

26
Q

Next step in Type 2 VWS after determining multimeres are abnormal

A

Genetic testing to differentiate Type 2 A vs. B

27
Q

Why is DDAVP contraindicated for Type 2B?

A

Can worsen thrombocytopenia

28
Q

Management of chronic frequent bleeding in VWS patients

A

weekly prophylaxis with VWF concentrate

29
Q

Perioperative FVIII + VWF goal for VWD for major surgeries

A

Target both Factor VIII and VWF activity levels of >0.50 IU/mL for at least 3 days following major surgery (ASH guidelines)
*

30
Q

Characteristic of all Type 2

A

VWF activity is decreased out of proportion to VWF antigen

31
Q

Higher VWF propeptide to antigen level suggests

A
  • Type 1c (protein is being made but being cleared)

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