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-   -   VIPoma treated with octreotide (https://www.usmle-forums.com/usmle-step-1-forum/7017-vipoma-treated-octreotide.html)

aktorque 02-27-2011 07:29 PM

VIPoma treated with octreotide
 
A patient presents with persistent diarrhea. Further examination reveals that the cause of this patient's diarrhea is a VIPoma. The patient is prescribed octreotide and blood work is conducted two weeks later. Which is the following would be observed in the patient's blood work?


A. ↑ Somatostatin
B. ↑ IGF-1
C. ↓ GH
D. ↑ VIP
E. ↑ K+

doctorsmonsters 02-27-2011 07:42 PM

I am gonna go with C, as octreotide is an analogue of somatostatin.

AndyG83 02-27-2011 07:48 PM

C
 
C - like mentioned it's a somatostatin analog and will therefor inhibit GH

I hope I'm right, or else I'm in trouble, I have a pharm test tomorrow on Endocrine, Reproductive, Respiratory, GI, & Musculoskeletal drugs!!!


:rolleyes::rolleyes::rolleyes:

apx85 02-28-2011 08:52 AM

C
 
Octreotide is a somatostatin analog that will inhibit pacreatic/gastric secretions in this patient

Somatostatin also works in the anterior pituitary to inhibit release of GH. Therefore, octreotide will decrease the secretion of GH by the anterior pituitary.

NOTE: IGF-1 has a longer half-life in serum than GH so it is a more reliable measure of GH secretion since GH is secreted in a pulsatile fashion. I would have liked to see decreased IGF-1 as the answer but decreased GH works as well.

aktorque- can you include in your explanation how K+ levels could be affected? not sure how that relates if at all.

Thanks!

aktorque 02-28-2011 11:23 AM

C) ↓ gh
 
Very nice, all of you are answered correct

Correct ans is C) ↓ GH


Octreotide is a somatostatin analogue. Accordingly, it will have a similar effect on the GH axis as somatostatin. GH will decrease in response to octreotide. Consequently, IGF-1 will also decrease since its secretion is downstream of GH stimulation at the liver (apx8 mentioned above). VIP will decrease since it too is inhibited by somatostatin (the reason for giving octreotide as a treatment for VIPoma). And finally, somatostatin will decrease because ↓ GH.

@apx85 - Somatostatin has no effect on K+, its just there as a choice to confuse students.


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