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NBME 22 Answers

nbme22/Block 4/Question#44 (36.3 difficulty score)
A 10-year-old boy has bruised easily since ...
Prolonged prothrombin time🔍

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 +7  upvote downvote
submitted by seagull(1112),
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fI oyu 'nodt wnok htwa mlairoDuc dseo ekli yna mroaln nuhma. heT sufco on wath nripsia oends't d,o melany t'si nsoedt' feftca PT eimt and tsmo llsip 'otdn rnieaecs gnttolci ypcsiaeel(l htwi )nspiira. iTsh si hwo I goicl to the rtigh arw.esn

usmleuser007  If that's then thinking, then how would you differentiate between PT & PTT? +11  
ls3076  Why isn't "Decreased platelet count" correct? Aspirin does not decrease the platelet count, only inactivates platelets. +4  
drmohandes  Because dicumarol does not decrease platelet count either. +  
krewfoo99  @usmleuser007 Because the answer choice says decrease in PTT. If you take a heparin like drug then the PTT will increase. Drugs wont increase PTT (that would be procoagulant) +3  
pg32  I think usmleuser007 and is3076 were working form the perspective of not knowing what dicumerol was. If you were unsure what dicumarol was, there really wasn't a way to get this correct, contrary to @seagull's comment. You can't really rule out any of these as possible options because aspirin doesn't do any of them. +2  
snripper  yeah, it wouldn't work. We'll need to know with Dicumarol is. +3  
jackie_chan  Not true, the logic works. You gotta know what aspirin does at least, it interferes with COX1 irreversibly and inhibits platelet aggregation (kinda like an induced Glanzzman), all it does. PT, aPTT are functions of the coagulation cascade and the test itself is not an assessment of platelet function. Bleeding time/clotting time is an assessment of platelet function. A- decreased plasma fibrinogen concentration- not impacted B- decreased aPTT/partial- DECREASED, indicates you are hypercoaguable, not the case C- decreased platelet count- aspirin does not destroy platelets D- normal clotting time- no we established aspirin impacts clotting/bleeding time by preventing aggregation E- prolonged PT- answer, aspirin does not impact the coagulation factor cascades in the test +1  
teepot123  di'coumarin'ol +  

 +7  upvote downvote
submitted by adong(82),

Dicumarol is in the coumarin family which includes warfarin. It helps if you think about warfarin's brand name Coumadin. Coumadin, coumarin, dicumarol...all the other derivatives have COUM it in some fashion

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 +3  upvote downvote
submitted by azibird(73),

In what century is this question taking place?? Dicoumarol was replaced by warfarin in the mid-1950s! It's on the FDA's list of discontinued drug products!

From wikipedia: "Identified in 1940, dicoumarol became the prototype of the 4-hydroxycoumarin anticoagulant drug class. Dicoumarol itself, for a short time, was employed as a medicinal anticoagulant drug, but since the mid-1950s has been replaced by its simpler derivative warfarin, and other 4-hydroxycoumarin drugs."

Did the grandpa have some leftover dicoumarol in the cabinet from his DVT in the summer of 1949?? This question is absolutely ridiculous.

we need to know like 400 drugs in FA, and they choose the one that's not in there. thanks NBME

 +0  upvote downvote
submitted by zpatel(19),
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aCn yaneon lelt the ceetff of inripas no a ldoob lba evula (ie. FirTPn,iTT,bP rpucdt)?o

paperbackwriter  Aspirin only increases platelet aggregation (blocks COX1/2 --> decreased production of Thromboxane A2 --> decreased aggregation). That's why it only increases bleeding time and has no effect on PT, PTT, and fibrin products. PT and PTT are only affected if something messes the coagulation cascade. +  

 +0  upvote downvote
submitted by shutch94(0),

I get that bleeding time is a measurement of platelet function. Is clotting time a measurement of the coagulation cascade (PTT/PT)?

drdoom  yes, that's correct. +