need help with your account or subscription? click here to email us (or see the contact page)
join telegramNEW! discord
(Free 120)  NBME 30NEW! NBME 29NEW! NBME 28NEW! NBME 27NEW! NBME 26NEW! NBME 25NEW!
NBME 24  NBME 23  NBME 22  NBME 21  NBME 20  NBME 19  NBME 18  NBME 17  NBME 16  NBME 15  NBME 13 
(Step 2 CK Free 120)  Step 2 CK Form 8  Step 2 CK Form 7  Step 2 CK Form 6 
search for anything ⋅ score predictor (โ€œpredict me!โ€)
NBME 22 Answers

nbme22/Block 3/Question#16 (reveal difficulty score)
A 27-year-old woman comes to the physician ...
Antiphospholipid antibodies ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
tags:

 Login (or register) to see more


 +12  upvote downvote
submitted by โˆ—hayayah(1211)

Pregnancy + Hx of thrombosis --> think antiphospholipid syndrome

The PT and PTT are prolonged d/t interference from the antibodies to phospholipids. Thrombin time normal.

Had to find research articles about it so take it from here and don't waste your time...

 Login (or register) to see more
monoloco  yeah, iโ€™ve never heard of antiphospholipids increasing PT time ... +26
goldenwakosu  Not sure if that little detail was to throw us off. I think the point of the question was to ID antiphospholipid syndrome based on the clinical criteria (spontaneous abortion + thrombosis) +5
johnthurtjr  I actually went down a rabbit hole with this one recently - essentially in vitro findings =/= in vivo findings, clot-wise with anti-phospholipid antibodies. +4
link981  No mention of lupus anticoagulant, anticardiolipin, or anti Beta 2 antibodies. FA mentios prolonged PTT but nothing on PT. What a piece of shit question. But thanks to the dudes above who explained it +9
yb_26  UWorld mentioned "prolong aPTT (and sometimes PT)" in APS +5
oslerweberrendu  @yb_26 Can u please tell the QID because the one I have seen it says, "Although patients often have prolonged ptt (because the antiphospholipid interferes with ptt test), pt is normal." QID: 1298 +1
kevin  just to clarify, lupus anticoag is in antiphospholipid and presents with paradoxical increased ptt +/- pt despite increase risk thrombosis +2



 +2  upvote downvote
submitted by amphotericin(11)

how would you rule out C) dysfibrinogenemia? I first guessed APS but switched it because of the PT/PTT thing

 Login (or register) to see more
suckitnbme  You should be able to rule it out by the normal Thrombin time. Abnormal fibrinogen would have increased PT/PTT but also increased Thrombin time because the entire pathway is compromised by the inability of fibrinogen to be cleaved to functioning fibrin. +9



 +1  upvote downvote
submitted by โˆ—kms123(2)

How would we rule out antithrombin deficiency?

 Login (or register) to see more
sd22  PT, PRT, and TT normal in antithrombin deficiency. FA โ€˜20 pg. 428 +
sd22  PTT* lol autocorrect clearly hasnโ€™t been studying +



 +1  upvote downvote
submitted by โˆ—weirdmed51(30)

Summary (increase -I, NORMAL -N) + APS : PT-I, PTT-I, TT-N + Dysfibrinogenemia: PT-I, PTT-I, TT-I + Protein C defc : PT-N, PTT-N, TT-N

 Login (or register) to see more



 -1  upvote downvote
submitted by โˆ—rainlad(33)

How do you rule out Protein C deficiency in this case? doesn't that also increase risk of thrombosis and miscarriage?

 Login (or register) to see more
suckitnbme  @rainlad Protein C deficiency doesn't cause elevated PT and aPTT. I believe they're both normal and assays for the disease measure protein C activity. +6
drzed  Protein C is an anti-coagulant, so if you lack factor C, then you have MORE clotting factors. This means that the PT and PTT would not be prolonged. +6



Must-See Comments from nbme22

sacredazn on Unrearranged immunoglobulin gene
seagull on Decreased binding of RNA polymerase
seagull on Anticholinergic
liverdietrying on Release of stored thyroid hormone from a ...
mcl on Area labeled โ€˜Dโ€™
kernicterusthefrog on Displacement
keycompany on Negative nitrogen balance
joha961 on Displacement
imgdoc on Area labeled โ€˜Cโ€™ (Abducens nucleus, right)
alwaysanonymous on 25 mL/cm H2O
seagull on Glutamine
drdoom on 1 in 600
bubbles on Acute retroviral infection
usmleuser007 on Chi-square test

search for anything NEW!