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Old 02-23-2012
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Arrow NBME 1 Block 1 discussion

hey could explain Qs no 26 and 43 ...
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Q26:

Asking the relative risk. Basically you have to divide the percent of women with no children having breast CA by the percent of women with children having breast CA.

(180/1000) / (120/1500) = 2.25



Q43:

Angiogram of a vertebral Artery. You can see the 2 arteries joining to form 1 artery at the right edge, which will be the basilar artery. So the lesion is right before the 2 join, which would make it PICA.

PICA lesion cause lateral medullary syndrome and the only answer which would fit it is B, ataxic limb movements.
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Q5:

I think its B. ATP depletion is the first thing that happens in ischemic cells, leading to decreased activity of the Na/K ATPase which caused cellular swelling.


Q29:

I think it's C. Key word here being activity. Renin will be more active on the right renal artery than the renal vein.


Q40:

I think it's A. If you plot a line that best fits the distribution it would be a line going through the middle (45 degree angle). This shows a linear relationship between the 2 and +1.00 is the best answer.


Q 45:

I think it's C. Case fatality rate would mean number of specific cases divided by total fatalities. There is 1 fatality from recreational. Total fatalities are 69...........So 1/69
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Quote:
Originally Posted by haga View Post
Q5:

I think its B. ATP depletion is the first thing that happens in ischemic cells, leading to decreased activity of the Na/K ATPase which caused cellular swelling.


Q29:

I think it's C. Key word here being activity. Renin will be more active on the right renal artery than the renal vein.


Q40:

I think it's A. If you plot a line that best fits the distribution it would be a line going through the middle (45 degree angle). This shows a linear relationship between the 2 and +1.00 is the best answer.


Q 45:

I think it's C. Case fatality rate would mean number of specific cases divided by total fatalities. There is 1 fatality from recreational. Total fatalities are 69...........So 1/69
#5: i agree. less ATP -> decreased activity of Na/K-ATP-ase -> increased intracellular sodium -> water rushes in -> cell swelling.

#29: i agree. i also put C.

#40: answer key is correct. it's B. if it were A the dots would be closer together, hence signifying a very strong correlation. Here we see a loose correlation, hence the dots aren't so close together.

#45: answer key is correct. what you are explaining is total fatality rate, not case fatality rate. case fatality rate is number of deaths from that specific subcategory, therefore the denominator is 12, not 69.
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15: isn't follicular carcinoma "cold"? meaning it does not take up iodine? i think thats what I learned in Kaplan.

23: how do you approach this question to get the answer? i saw memory loss and some dementia and chose B. What tells you the answer is E?

38: how do you approach this one?

46: is this even written anywhere, in any textbook?
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Quote:
Originally Posted by Dr.NickRiviera View Post
15: isn't follicular carcinoma "cold"? meaning it does not take up iodine? i think thats what I learned in Kaplan.

23: how do you approach this question to get the answer? i saw memory loss and some dementia and chose B. What tells you the answer is E?

38: how do you approach this one?

46: is this even written anywhere, in any textbook?

Q15:

yes a cold nodule doesn't take up iodine but the rest of the thyroid will take it up. I think the reason they threw in the iodine uptake was so that you can differentiate between hypothyroidism and a tumor. Since the uptake rules out Hypo we can cross off Hashimotos and Granulomatous. Now we have to determine which tumor it is.

Follicular Adenoma is the Most common tumor (even though it is benign) and it is also the most common tumor presenting with a solitary cold nodule. These are important facts to associate with Follicular type.


Q23:

Well you have to know the differences between the different types. In Pick's there is a greater impact on personality, greater impulsiveness and loss of concentration. Another important clincher is grasp and snout reflex. When the frontal lobe is damaged there is a marked increase in both of these. They also mention only a mild loss in memory. Alzheimer's would have a marked loss of memory.


Q38:

Typical signs of depression.

disturbed sleep pattern with early waking
loss of concentration
appetite/weight change
loss of energy
guilt

all present in the stem.



Q46:

Not written in any book I've read, but not so hard to deduce from the rest of the options.
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Quote:
Originally Posted by Dr.NickRiviera View Post
15: isn't follicular carcinoma "cold"? meaning it does not take up iodine? i think thats what I learned in Kaplan.

23: how do you approach this question to get the answer? i saw memory loss and some dementia and chose B. What tells you the answer is E?

38: how do you approach this one?

46: is this even written anywhere, in any textbook?
Qs 15 ....The follicular adenoma of the thyroid is a common benign tumor of
the thyroid gland. They present as a solitary nodule, usually as a
painless mass. It may be found during a routine physical examination. A
physician may order a nuclear medicine thyroid scan which measures
uptake of radionucleotide labelled iodine. Adenomas are usually cold
nodules since they usually take up less radioactive iodine than normal
surrounding gland. On the other hand, about 10% of cold nodules are
malignant. Conversely, hot nodules are only rarely malignant. Warm
nodules are usually functioning adenomas.

Qs 23 is a picks disease , a frontotemporal lesion ... change in behaviour is the key see FA pg no 425

Qs 38 she has all the signs of depression , loss of interest in activities and friends , waking up early , staying alone ..

Qs 46 ..was in my gynac textbook and had learned this for a Qs on vasectomy .....
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Quote:
Originally Posted by haga View Post
Q15:

yes a cold nodule doesn't take up iodine but the rest of the thyroid will take it up. I think the reason they threw in the iodine uptake was so that you can differentiate between hypothyroidism and a tumor. Since the uptake rules out Hypo we can cross off Hashimotos and Granulomatous. Now we have to determine which tumor it is.

Follicular Adenoma is the Most common tumor (even though it is benign) and it is also the most common tumor presenting with a solitary cold nodule. These are important facts to associate with Follicular type.


Q23:

Well you have to know the differences between the different types. In Pick's there is a greater impact on personality, greater impulsiveness and loss of concentration. Another important clincher is grasp and snout reflex. When the frontal lobe is damaged there is a marked increase in both of these. They also mention only a mild loss in memory. Alzheimer's would have a marked loss of memory.


Q38:

Typical signs of depression.

disturbed sleep pattern with early waking
loss of concentration
appetite/weight change
loss of energy
guilt

all present in the stem.



Q46:

Not written in any book I've read, but not so hard to deduce from the rest of the options.
so hypothyroid does not take up iodine, but tumors do? thats what im looking at when they mention taking or not taking up iodine?
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Hypo will not take up Iodine.

Hyper/Normal tissue will take it up.


Nothing to do with tumors. That was just a way to rule out hypo, as there were 2 diseases causing hypo in the answers. There are different types of tumors, some take it up, some don't.
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Quote:
Originally Posted by haga View Post
Hypo will not take up Iodine.

Hyper/Normal tissue will take it up.


Nothing to do with tumors. That was just a way to rule out hypo, as there were 2 diseases causing hypo in the answers. There are different types of tumors, some take it up, some don't.
ok that makes sense, thanks.
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[QUOTE=haga;96381]Q26:

Asking the relative risk. Basically you have to divide the percent of women with no children having breast CA by the percent of women with children having breast CA.

(180/1000) / (120/1500) = 2.25


thanks , understood the Qs 43

but how do you decide whether to calculate it this way or by the RR formulae a/a+b by c/c+d ???
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[QUOTE=Hitman;96417]
Quote:
Originally Posted by haga View Post
Q26:

Asking the relative risk. Basically you have to divide the percent of women with no children having breast CA by the percent of women with children having breast CA.

(180/1000) / (120/1500) = 2.25


thanks , understood the Qs 43

but how do you decide whether to calculate it this way or by the RR formulae a/a+b by c/c+d ???
that sounds like a positive predictive value formula (or one of those sensitivity, specificity ones), not relative risk.
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[QUOTE=Dr.NickRiviera;96421]
Quote:
Originally Posted by Hitman View Post

that sounds like a positive predictive value formula (or one of those sensitivity, specificity ones), not relative risk.
no its a RR formulae from FA pg no 52 ......
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[QUOTE=Hitman;96422]
Quote:
Originally Posted by Dr.NickRiviera View Post

no its a RR formulae from FA pg no 52 ......
oh you mean divide when you say 'by'

yea its the same formula.
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a = effected and has the cause
d = unaffected and doesnt have the cause

so a = cancer patients with kids
d = no cancer and no kids
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[QUOTE=Dr.NickRiviera;96425]
Quote:
Originally Posted by Hitman View Post

oh you mean divide when you say 'by'

yea its the same formula.

didnot get it , i put a, b, c, d into those blocks and got A as the ans

do you change the block as they ask the ratio of childless verses childbearing ??
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[QUOTE=Hitman;96428]
Quote:
Originally Posted by Dr.NickRiviera View Post


didnot get it , i put a, b, c, d into those blocks and got A as the ans

do you change the block as they ask the ratio of childless verses childbearing ??
i dont have the question in front of me but sounds like what they did is move the table around to trick you
don't memorize a,b,c,d as quadrants of the table
remember a as effect and with cause (in this case, a cancer patient with children) and d as uneffected and no cause (ie. no cancer and no children).

b will be ummm effected but without the cause (cancer patient with no kids)
c will be uneffected with cause (no cancer with kids)
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Quote:
Originally Posted by Dr.NickRiviera View Post
a = effected and has the cause
d = unaffected and doesnt have the cause

so a = cancer patients with kids
d = no cancer and no kids

yup did the same thing , a = 120 , b= 180 , c=1380 , d= 820 ..

now put it into a/a+b divided by c/c+d

got A .....
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yup did the same thing , a = 120 , b= 180 , c=1380 , d= 820 ..

now put it into a/a+b divided by c/c+d

got A .....
one sec, ill go grab my papers
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ok now that i see the question i see what its asking. that formula isnt what we use.
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ok now that i see the question i see what its asking. that formula isnt what we use.

so what is it ? how do you decide which to use ? it clearly says relative risk ?

or just becoz theres a bracket saying risk ratio so ?
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breast cancer in childless women = 180/1000 = 0.18
breast cancer in women w/ children = 120/1380 = 0.08

RR = 0.18 / 0.08 = 2.25 !
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so what is it ? how do you decide which to use ? it clearly says relative risk ?

or just becoz theres a bracket saying risk ratio so ?
honestly i dont even think of the equations, i think think it out and try to deduce it mathematically.

the formula works here if you take a as breast cancer with children and c as breast cancer without women. essentially looking vertically across the table instead of the horizontal example given in FA on page 52.
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Quote:
Originally Posted by Dr.NickRiviera View Post
honestly i dont even think of the equations, i think think it out and try to deduce it mathematically.

the formula works here if you take a as breast cancer with children and c as breast cancer without women. essentially looking vertically across the table instead of the horizontal example given in FA on page 52.
i see , may be its not about the formula .......

thanks ..
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Quote:
Originally Posted by Hitman View Post
Q26:

Asking the relative risk. Basically you have to divide the percent of women with no children having breast CA by the percent of women with children having breast CA.

(180/1000) / (120/1500) = 2.25


thanks , understood the Qs 43

but how do you decide whether to calculate it this way or by the RR formulae a/a+b by c/c+d ???

the table isn't arranged properly. Before you can use that formula you have to arrange the table in that format. Risk factor with disease being first.

...........................Breast Cancer
...........................Y.............N

No Children...........180..........820

Children................120..........1380


Use that formula now and you will get the answer. Remember when using any formulas always ensure the table represents "A" as being risk factor with disease.
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