UREA:Creatinine Ratio ??

[ssstrong]

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Hi

Please Help Me in This Question :

A Patient with Serum Urea= 80 mg/dl and serum creatinine = 0.9 mg/dl, these results indicates :

A) post-renal uremia.
B) Normal GFR.
C) GIT Hemorrhage.
D) Circulatory Shock.

Plz for every CHOSE is it true or flase , and help me with little explanation for the answer.

Thank You

 

[Tiger26]

Hi

Please Help Me in This Question :

A Patient with Serum Urea= 80 mg/dl and serum creatinine = 0.9 mg/dl, these results indicates :

A) post-renal uremia.
B) Normal GFR.
C) GIT Hemorrhage.
D) Circulatory Shock.

Plz for every CHOSE is it true or flase , and help me with little explanation for the answer.

Thank You

More than likely, it indicates hemorrhage, although I'd like to know a little patient history. In any hypovolemic state, you're kidneys work for a period of time, and seek to reabsorb urea due to the general fluid deficit, however, creatinine is not reabsorbed. Therefore, you get an elevated (i.e. >20) BUN:creatinine ratio. If there's a problem with the kidney itself, there's a problem with urea reabsorption, so urea and creatinine are excreted at a similar rate, giving you a lower ratio.

 

[thechad]

This sounds like circulatory shock to me. Pre-renal heart failure leads to the blood just kind of sitting in the tubules, and so more urea is reabsorbed, but I could be wrong.

 

[bydotte]

circulatory shock. sure hypovolemia could do it, but not via a hemorrhage.

 

[bodonid]

a BUN/creatinine ratio of 30 or above has a sensitivity of 68.8% for upper GI bleeding and a specificity of 98%- I would assume this only increases with increasing ratio- and this ratio is ~90

 

[Blondnuttyboy]

Inc. BUN:Crea can take place anytime you reduce your gfr but maintain normal functioning tubules (i.e. BUN reabsorption is not affected)

With that being said, I can envision by it could be hem. or shock...it could even be post-renal if an obstruction caused backflow causing inc. reabsorption...

for sure not a normal GFR

 

[ssstrong]

Thank You Very Much to all of you guys ,,

i want to tell you that i was asked this question in the Biochemistry exam "Renal Fun. Test" , the correct answers that POST-Reanl Uremia, NORMAL GFR and Shock are all wrong , about the Hem. i don't know the correct answer yet.

Thanks Again for your help guys.

Regards

Saman SarKo

 

[NRAI2001]

Thank You Very Much to all of you guys ,,

i want to tell you that i was asked this question in the Biochemistry exam "Renal Fun. Test" , the correct answers that POST-Reanl Uremia, NORMAL GFR and Shock are all wrong , about the Hem. i don't know the correct answer yet.

Thanks Again for your help guys.

Regards

Saman SarKo

Ya i dont know what post renal uremia actually entails...but I always thought that in hypovolumic/dehydration states that BUN and Creatinine both go up (creatinine as falsely elevated due to volume loss and BUN do to volume loss and due to retention).. I think one of our path profs mentioned that it was more the ratio of UREA:creatinine that was more important; it should normally be about 20:1.

 

[NRAI2001]

Ya i dont know what post renal uremia actually entails...but I always thought that in hypovolumic/dehydration states that BUN and Creatinine both go up (creatinine as falsely elevated due to volume loss and BUN do to volume loss and due to retention).. I think one of our path profs mentioned that it was more the ratio of UREA:creatinine that was more important; it should normally be about 20:1.

Am i correct with this statement??

What can cause post renal uremia?? Any obstruction to flow (tubules, ureters, bladder, urethra) would also cause a decrease in GFR wouldnt it?

 

[silas2642]

Hi

Please Help Me in This Question :

A Patient with Serum Urea= 80 mg/dl and serum creatinine = 0.9 mg/dl, these results indicates :

A) post-renal uremia.
B) Normal GFR.
C) GIT Hemorrhage.
D) Circulatory Shock.

Plz for every CHOSE is it true or flase , and help me with little explanation for the answer.

Thank You

So I KNOW that you could find the answer in Golgan in the renal section. I don't have Golgan with me, as I'm on vacation, but I think that the normal BUN:creatinine ratio is about 15.

With pre-renal azotemia, doesn't the BUN:creatinine ratio go down because the tubules reabsorb urea in order to conserve water?

With post-renal azotemia, I believe the BUN:creatinine ratio is going to be greater than 15 because volume isn't a problem so you're not reabsorbing urea.

I think that with renal azotemia the BUN:creatinine ratio is about 15, but I may be completely off my rocker.

Bueller?

 

[bodonid]

nm

 

[rup47]

So I KNOW that you could find the answer in Golgan in the renal section. I don't have Golgan with me, as I'm on vacation, but I think that the normal BUN:creatinine ratio is about 15.

With pre-renal azotemia, doesn't the BUN:creatinine ratio go down because the tubules reabsorb urea in order to conserve water?

With post-renal azotemia, I believe the BUN:creatinine ratio is going to be greater than 15 because volume isn't a problem so you're not reabsorbing urea.

I think that with renal azotemia the BUN:creatinine ratio is about 15, but I may be completely off my rocker.

Bueller?

pre-renal: Bun/creat >20
renal and post renal: Bun and Creat both are typically effected roughly the same so they are just both elevated above their normal values.

Pre-renal causes primarly being reduced blood flow to the kidney which means various types of shock including hemorrhagic shock would be expected to cause elevated bun/creat ratios above 20 to 1

 

[labgirl]

It's GIT hemorrhage. As you digest blood (i.e. protein), the by product is urea, causing the BUN to go up and Creat to stay normal. Being a pre-med, I may not have explained this correctly, so someone correct me there if necessary, but my vote is definately for GIT hemorrhage.

 

[rup47]

It's GIT hemorrhage. As you digest blood (i.e. protein), the by product is urea, causing the BUN to go up and Creat to stay normal. Being a pre-med, I may not have explained this correctly, so someone correct me there if necessary, but my vote is definately for GIT hemorrhage.

You are correct with GI hemorrhage but your mechanism is off. Good thinking though, you have plenty of time to learn all of this in medical school though. 🙂

In a GI hemorrhage most of the blood will be excreted through the GI tract. That is why in a GI bleed the patient is not jaundiced.

A GI bleed will lead to pre-renal failure/azotemia because of the acute loss of blood resulting in a decreased intravascular blood volume. This results in decreased blood flow to the kidney and resulting decrease in the GFR. Since GFR is decreased both BUN and creatinine will be excreted at a slower rate. HOwever, urea is reabsorbed in the kidney, createnine is not. Since the kidney is trying to conserve as much intravasuclar volume as possilbe reabsorption of urea will increase. Because of this the ratio of Bun/creatinine is increased. Any cause of pre-renal failure will lead to a increased bun/creat ratio.

 

[Instatewaiter]

Both GI bleeds and shock cause prerenal azotemia so both have BUN/Cr > 20 because they are prerenal.

GI bleeds additionally increase BUN thus the ratio may be even higher.

Answer: GI bleed.

 

[bodonid]

You are correct with GI hemorrhage but your mechanism is off. Good thinking though, you have plenty of time to learn all of this in medical school though. 🙂

In a GI hemorrhage most of the blood will be excreted through the GI tract. That is why in a GI bleed the patient is not jaundiced.

A GI bleed will lead to pre-renal failure/azotemia because of the acute loss of blood resulting in a decreased intravascular blood volume. This results in decreased blood flow to the kidney and resulting decrease in the GFR. Since GFR is decreased both BUN and creatinine will be excreted at a slower rate. HOwever, urea is reabsorbed in the kidney, createnine is not. Since the kidney is trying to conserve as much intravasuclar volume as possilbe reabsorption of urea will increase. Because of this the ratio of Bun/creatinine is increased. Any cause of pre-renal failure will lead to a increased bun/creat ratio.

that does not address the question of why GI bleed causes the ratio to rise so much more than hypovolemia, though. But good explanation.

 

[rup47]

that does not address the question of why GI bleed causes the ratio to rise so much more than hypovolemia, though. But good explanation.

I didn't realize that a bun/creat above 30, i believe, is more specific for a GI bleed as the cause of pre-renal failure. I just assumed any bun/creat above 20 was pre-renal failure of any cause 99% of the time. I guess the blood that does get digested does contribute to the elevated urea which is why with a bun of 80 and creat of 0.9 they are looking for the specific cause to be gi hemorrhage.

 

[mipp0]

As a pre-med, I just wanted to say you guys


SOUND SO COOL.

Sorry about the tangent. Carry on.

 

[Polish Farmer]

Pre-renal azotemia is as classified above, but the Cr would bump as well. You are looking at a GIT hemorrhage

3 reasons for BUN>>>Cr:
GIB
Steroids
TPN

Classic board question

 

[gluon999]

Agree with those who said GIT hemorrhage. The very high BUN is due to urea coming from blood.

It can't be circulatory collapse b/c that would most likely cause acute renal failure, causing a rise in Creatinine too. Creatinine in the above example is normal.