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* Glanzmann vs. Bernard Soulier vs. von Willebrand
 #797053  
  usmleprepgal - 01/01/15 15:36
 
 
Let's get these 3 mixed up no longer!!

Ok, had to write this out and share because I have trouble remembering it.

Baseline knowledge: Ristocetin is a molecule that allows vWF and GPIb to bind together. It's like a match maker for these two molecules. In the absence of either of these components, the ristocetin result will be abnormal.

------Platelet adhesion impairments-----------

von Willebrand disease: genetic (most common of all 3)
Presentation: Mucosal and increased skin bleeding
Differentiating factor: Normal platelet count. Normal Pt & aPTT (in comparison to Hemophilia A)
Lab: Abnormal ristocetin test (there's no vWF!). Normal platelet count.
Tx: Desmopressin (ADH analog) that increases vWF release from Weibel-Palade bodies!



Bernard Soulier syndrome:
Presentation: Mucosal and increased skin bleeding
Differentiating factor: presents in the same fashion as vWF EXCEPT for three features: a mild thrombocytopenia w/ enlarged platelets. (Pathoma says "Big Suckers" for "B"ernard "S"soulier syndrome. )
Lab:genetic GPIb deficiency (the primary vWF receptor) Low platelet count.
Ristocetin test: Abnormal (there's no GPIb!)

So notice, to differentiate b/w the first 2 conditions you'll *need* lab/ genetic results. So if you see a question with these answer choice, best bet may just to go directly to scan for test results first.

-----------Platelet aggregation---------

Glanzmaan thrombasthenia:
Lab: genetic GPIIb/3a deficiencY (the receptor for both vWF and fibrinogen)
Ristocetin test: NORMAL ristocetin!


So for example, say I gave you a pt's test result with the following:
Agonist Response
Epinephrine Normal aggregation
Adenosine 5c-diphosphate Normal aggregation
Collagen Normal aggregation
Arachidonic acid Normal aggregation
Ristocetin Absent aggregation
Normal plasma Absent aggregation

Which of the following of the 3 would you consider?

You'd have to think of either vWF disease or Bernard soulier!
 
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173545
  usmleprepgal - 01/01/15 15:44
 
 
Summary:

Bernard Soulier Syndrome=Slight thrombocytopenia,Inc BT,subnormal result of ristocetin platelet aggregation,Giant megakaryoctes are hall mark

Von Willebrand Disease=Platelet count nl,Inc BT,Inc PTT, normal PT, subnormal ristocetin test

Hemophilia= Platelet count nl,Inc BT, Increased PTT and PT,

C.Glanzman's Thrombasthenia=Platelet count nl, Ptt normal Inc BT,ADP test subnormal, normal ristocetin
 
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173548
  usmleprepgal - 01/01/15 15:46
 
 

Hemophilia should read = Platelet count nl,Inc BT, Increased PTT and NORMAL PT,
 
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173552
  rosemaryusmle - 01/01/15 15:57
 
  thankyou .  
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173571
  haaaaa - 01/01/15 16:27
 
  thank you @usmleprepgal, I always get confused with these.  
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173589
  medicus - 01/01/15 17:41
 
  @Usmleprepgal: BT is not prolonged in hemophilia.  
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173591
  usmleprepgal - 01/01/15 17:49
 
 

Ah, it sure isn't!! Thank you medicus!

I read in a step 1 secrets book that Hemophilia A presents very similar to vWF disease, so I assumed it was similar stats but....it's really quite different 't. Thank you so much for the correction. Pathoma backed up what you're saying.

So Hemophilia should read = Platelet count nl,BT normal, Increased PTT and NORMAL PT.

vwF = platelet count normal, INC Btime, increased PTT and normal PT.

I honestly never realized that bleeding time is what differentiated hemophilia A and VwF. ...

 
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173593
  medicus - 01/01/15 17:57
 
  You are welcome. Yeah it does. I saw it in UW. Will let you know which Q ID I am talking about.  
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173594
  medicus - 01/01/15 17:59
 
  Its UW Q ID 1923  
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173727
  zeeviq - 01/02/15 13:17
 
  @usmleprepgal GPIIb/IIIa is receptor only for fibrinogen .It helps in platelet aggregation .
Receptor for vWF is GP1b.

Just a trivia that Ristocetin is an antibiotic that that induces platelet agglutination.
 
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* Re:Glanzmann vs. Bernard Soulier vs. von Willebra
#3173728
  zeeviq - 01/02/15 13:18
 
  *platelet aggregation  
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