Clotting deficiency question - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
USMLE Articles
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam

Thread Tools Search this Thread Display Modes
Old 04-08-2015
USMLE Forums Newbie
Steps History: ---
Posts: 1
Threads: 1
Thanked 0 Times in 0 Posts
Reputation: 10
Default Clotting deficiency question

FA 2015 P. 397 notes that Glanzmann's thrombasthenia is the result of a defect in GpIIb/IIIa.

Ristocetin, which used to diagnose some bleeding disorders, is noted to basically act as vWF in an unknown fashion. Normal bleeding time with ristocetin diagnoses vWF deficiency.

The notes then say that agglutination does occur with ristocetin assay.

How does this work if ristocetin only affects vWF, which is only involved in platelet adhesion, whereas GpIIb/IIIa is solely platelet aggregation?

Any ideas would be welcome
Reply With Quote Quick reply to this message

Old 04-09-2015
USMLE Forums Addict
Steps History: Not yet
Posts: 187
Threads: 18
Thanked 45 Times in 41 Posts
Reputation: 55

so this is what ive understood. Ristocetin is an antibiotic derivative which is now used to diagnose 2 conditions: VWD(where theres deficiency of this factor) and bernard soulier syndrome (where theres a defect in the receptor for vwf = gp1b)

now we must know that ristocetin basically cause vwf to bind to gp1b on the platelets and cause agglutination

if ristocetin is added to a blood which lacks the factor vwf or its receptor = agglutination will NOT occur (no clumping)

In FA i think its trying to say or rather differentiate between diagnoses of VWD and glanzmann, that in case of glanzman it has nothing to do with vwf so if u add ristocetin, clumping will occur

whereas in VWD , there is no factor, hence no clumping
Reply With Quote Quick reply to this message
The above post was thanked by:
CleverFOX (04-10-2015)


Quick Reply

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Where you live. Leave blank if you don't want to tell.


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Clotting screening tests, Q ag2011n USMLE Step 2 CK Forum 8 2 Weeks Ago 12:29 AM
Thiamine Deficiency Question m82_ghasemi USMLE Step 1 Forum 6 09-22-2011 12:19 PM
Vitamin deficiency picture question bebix USMLE Step 1 Forum 4 05-29-2011 05:16 AM
LMWH acts on which clotting factor and how it is monitored? hana USMLE Step 1 Forum 3 01-25-2011 10:31 AM
Clotting Lab Results of this case? Kabutar111 USMLE Step 1 Forum 5 08-12-2010 10:51 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)