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

#1
03-06-2012
 USMLE Forums Veteran Steps History: Not yet Posts: 270 Threads: 34 Thanked 221 Times in 119 Posts Reputation: 231
NBME 4 Block 1

Q17:
I picked C. So why do we multiply the 2 percentages rather than add them. Since they are percentages and we are equating them to a total population of 100, shouldn't we add them???

Q21:
I picked F. Ok so I am a little confused here. In the stem they are describing UML. So shouldn't that be the anterior horn lesion which will cause this problem???

Q40:
How do you calculate this??

Q41:
Ok I got the right answer based on the stem. What are they showing in the image, what is that on the LT side of the picture??

#2
03-06-2012
 USMLE Forums Master Steps History: Not yet Posts: 928 Threads: 17 Thanked 538 Times in 375 Posts Reputation: 548

Qs 17 I found the ans to be D .... No needed to treat is = 1/Absolute risk reduction

so Absolute risk reduction = event rate (control ) - event rate ( treatment )

so its = 10.1 % - 5.4% =( 10.1 % - 5.4 )/100

now NNT = 1/Absolute risk so 1/( 10.1 % - 5.4 )/100 = 100 / ( 10.1 % - 5.4 ) = 21

the method of calculation of Absolute risk is correct as i had the similar Qs in UW which i have written in FA

Qs 21 its H ....... yes its a UMN lesion so its CST lesion ...... ant horn lesion results in LMN as in amylotrophic lateraL sclerosis ...

Qs 40 . its simple Gfr = K ( Pgc - Pbc ) - ( # gc - # bc )

so = 10 ( 45 - 12 ) - ( 23 - 0 ) = 30

Qs 41 could be the renal capsule or some muscle fibre dont know for sure

need help with 47 , 48 ....

45 is B and 46 is C ........ check this once .....
#3
03-06-2012
 USMLE Forums Veteran Steps History: Not yet Posts: 270 Threads: 34 Thanked 221 Times in 119 Posts Reputation: 231

Q45:
B is right

Q46:
C is right

Q47:
Childhood irradiation increases risk of Papillary CA of thyroid (in FA). It is the long term complication. So G, palpation of thyroid gland is a must on physical exam.

Q48:
Remember that one question from the other NBME....L and D form. They are testing the same principle here. The structure is the same as they tell you in the stem, but the form is different so will not be broken down as quickly.

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