q5! - sarim

[ArchivalUser]

A 42 y/o female complains of fatigue, poor concentration, and weight gain over the last several months. Lab evaluation reveals high serum TSH and low T3 and T4 levels. Supplementing T3 to this pt would most likely result in which of the following ?

.. TSH …. T3 …. Reverse T3 …... T4

A-Decr …. Incr …….. Incr ……….. NC
B-Decr .... Incr ……… NC ……..…. NC
C-Decr …. Incr ……… Incr ……….. Incr
D-NC ……. Incr ……… NC ………..… NC
E-Incr ..... NC ………. Incr ……….. Incr

NC = No Change

[ArchivalUser]

BB

[ArchivalUser]

DDD

[ArchivalUser]

dd

[ArchivalUser]

Right answer is B

[ArchivalUser]

BBB, i made a mistake. thanks.

[ArchivalUser]

The correct answer choice is not in the options given. This is Uworld Q.
Correct answer is:

TSH (decrease)
T3 (increase)
rT3 (decrease)
T4 (decrease)

Thanks for the question.

[ArchivalUser]

tonye
isnt it the same thing?
rT3 and T4 were decreased before giving T3. so they remained decreased (not changed NC) even after giving T3..
the only difference is that TSH decreased due to negative feedback.
so basically what your saying is same as answer choice B

[ArchivalUser]

"B" is correct. Thanks for sharing the explanations

-Supplemental T3 --> Negative Feedback on Anter Pituitary --> “Decreased TSH”

-In the peripheral tissues T4 can be converted to T3 and Reverse T3

-But T3 can NOT be converted to rT3 and T4
Therefore “Exogenous T3” administration cause “Decreased TSH”, but no effect on T4 and rT3.

[ArchivalUser]

just confirming, T3 and T4 can cause neg feedback on TSH right? thanks for explanation.