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  #1  
Old 06-29-2011
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Kidney Renin-secreting tumor..what would you expect?

A patient complains of headaches, and an examination reveals that her blood pressure is 175/112 mmHg. Laboratory tests give the following results:

Plasma renin activity = 11.5 ng (normal = 1)
Plasma Na+ = 144
Plasma K+ = 3.4

A magnetic resonance imaging procedure suggests that she has a renin-secreting tumor. Which of the following changes would you expect, compared with normal?


Renin-secreting tumor..what would you expect?-screen-shot-2011-06-29-8.16.45-pm.png
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A) A
B) B
C) C
D) D
E) E
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  #2  
Old 06-29-2011
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I think D)

Renin will constrict efferent, so decreases RPF so therefore FF (GFR/RPF) should go up (Inc. GFR / Dec. RPF).

Because the efferent arteriole is constricted, it will increase Hydrostatic pressure, so we're left with B) or D)

If Glomerular Capillary Hydrostatic Pressure goes up, therewill be a decreased filtration F, so thus that can't be it.. so I think we're left with D)

Unless i'm making a huge mistake with all these..
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Quote:
Originally Posted by patelMD View Post
I think D)

Renin will constrict efferent, so decreases RPF so therefore FF (GFR/RPF) should go up (Inc. GFR / Dec. RPF).

Because the efferent arteriole is constricted, it will increase Hydrostatic pressure, so we're left with B) or D)

If Glomerular Capillary Hydrostatic Pressure goes up, therewill be a decreased filtration F, so thus that can't be it.. so I think we're left with D)

Unless i'm making a huge mistake with all these..
I also think is D)
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Old 06-29-2011
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[QUOTE=bebix;50267]A patient complains of headaches, and an examination reveals that her blood pressure is 175/112 mmHg. Laboratory tests give the following results:

Plasma renin activity = 11.5 ng (normal = 1)
Plasma Na+ = 144
Plasma K+ = 3.4

A magnetic resonance imaging procedure suggests that she has a renin-secreting tumor. Which of the following changes would you expect, compared with normal?


Attachment 1633

A) A
B) B
C) C
D) D
E) E
i think it's D too
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  #5  
Old 06-29-2011
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almost there!...
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Old 06-29-2011
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Quote:
Originally Posted by bebix View Post
A patient complains of headaches, and an examination reveals that her blood pressure is 175/112 mmHg. Laboratory tests give the following results:

Plasma renin activity = 11.5 ng (normal = 1)
Plasma Na+ = 144
Plasma K+ = 3.4

A magnetic resonance imaging procedure suggests that she has a renin-secreting tumor. Which of the following changes would you expect, compared with normal?


Attachment 1633
click image to enlarge

A) A
B) B
C) C
D) D
E) E
i think its E. Increased Renin, with decrese renal blood flow, hence decrease capillary hydrostatic pressure and decrease GFR and FF.
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FF= GFR/RPF

efferent arterilar constriction causes Increase in GFR and capillarypressure,,,n decreas in RPF



s its A
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Old 06-29-2011
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Quote:
Originally Posted by bebix View Post
A patient complains of headaches, and an examination reveals that her blood pressure is 175/112 mmHg. Laboratory tests give the following results:

Plasma renin activity = 11.5 ng (normal = 1)
Plasma Na+ = 144
Plasma K+ = 3.4

A magnetic resonance imaging procedure suggests that she has a renin-secreting tumor. Which of the following changes would you expect, compared with normal?


Attachment 1633
click image to enlarge

A) A
B) B
C) C
D) D
E) E
...I will go for E)...:sorry:
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  #9  
Old 06-29-2011
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i say its D
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Maybe B. Renin would cause ATII which would constrict the efferent arteriole, so there would more back flow of fluid in the glomerular capillaries, increased Glomerular capillary hydrostatic pressure, so increased GFR, increased FF, and Aldosterone formed in response would cause increased Na reabsorption from the DCT, which would also cause increased flow of H20 so increased fluid in peritubular capillaries so increased peritubular capillary hydrostatic pressure..

does that sound right? im not too good at renal, so...
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Old 06-29-2011
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I think its A
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I think A:
renin constricts efferent arteriole --> decrease RBF-->increase FF since FF= GFR/RBF --> increased glomerular hydrostatic pressure--> decreased peritubular capillary pressure (because if the glomerular hydrostatic pressure is increased, that means the more fluid gets filtered out and the blood left behind is more concentrated with protein. Therefore the blood that eventually gets to the peritubular capillaries has more protein i.e. high oncotic pressure and low hydrostatic pressure).
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never mind...
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Aaaaaaaaaaa
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  #15  
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Default E)

I dnt think the FF increases as u say, FF=GFR /RPF only when the afferent artery is perfusing normally and any efferent arteriole constriction can increase FF by making the blood stay for a while in the capillaries and more fluid is filtered,but here its a renin secreting tumor in the JG cells of afferent ateriole so there is less perfusion to the glomerulus and filtration fraction will not increase !!!



jus a thought,correct me if i am wrong Bebix where are u ?
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Correct Answer correct answer

The correct answer is A)

Excessive secretion of renin leads to the formation of large amounts of AII, which in turn causes marked constriction of glomerular arterioles, having a greater effect on efferent arterioles than afferent. This reduces renal blood flow, increases glomerular hydrostatic pressure, and decreases peritubular capillary hydrostatic pressure. Because constriction of efferent arterioles reduces renal blood flow more than GFR, the filtration fraction (ratio of GFR to renal plasma flow) increases.
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  #17  
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yes its A
thanx for bebix for the explanation
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hmmm, i see what you guys mean now, i might have over-read into the question, as usual...was thinking that the sodium is borderline with high and the potassium is borderline with low so perhaps aldosterone had a role to play which would lead to na abso in the peritubular cap and then increase in the water as well, eventually increase in the hydrostatic pressure...now i understand that that would happen only towards the dct and would in all prbability be stretching things too much...
thanks for the great responses heights, bebix!
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Quote:
Originally Posted by bebix View Post
The correct answer is A)

Excessive secretion of renin leads to the formation of large amounts of AII, which in turn causes marked constriction of glomerular arterioles, having a greater effect on efferent arterioles than afferent. This reduces renal blood flow, increases glomerular hydrostatic pressure, and decreases peritubular capillary hydrostatic pressure. Because constriction of efferent arterioles reduces renal blood flow more than GFR, the filtration fraction (ratio of GFR to renal plasma flow) increases.
This doesn't make sense to me, if you constrict efferent, then more blood will ''build up'' proximal to the constriction which is where the glomerulus is, this INCREASES hydrostatic pressure (peritubular). So the other apposing force Capillary Hydrostatic pressure has to go down, since if both apposing forces are increased, fluid wouldn't move anywhere....

Does anyone else see what I am saying?
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Quote:
Originally Posted by patelMD View Post
This doesn't make sense to me, if you constrict efferent, then more blood will ''build up'' proximal to the constriction which is where the glomerulus is, this INCREASES hydrostatic pressure (peritubular). So the other apposing force Capillary Hydrostatic pressure has to go down, since if both apposing forces are increased, fluid wouldn't move anywhere....

Does anyone else see what I am saying?
actually, will decrease hydrostatic pressure...the peritubular capillar start after the efferent arterioles...
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actually, will decrease hydrostatic pressure...the peritubular capillar start after the efferent arterioles...
*facepalm*, ahh that makes sense!
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Old 07-01-2011
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Quote:
Originally Posted by patelMD View Post
*facepalm*, ahh that makes sense!
For anyone who is interested here is a picture:

Renin-secreting tumor..what would you expect?-33212-0550x0475.jpg
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Old 07-01-2011
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what a question..
it cleared and repeated ma favourite unit..
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