Term
| Prerenal BUN to Creatine, and why this is so: |
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Definition
| BUN : Creatinine ratio. > 20:1 because in prerenal failure, one or both of the kidneys "knows" that it is not getting enough fluid, and so the kidneys reabsorb sodium and water in an attempt to increase intravscular volume to correct the perceived hypovolemia. |
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Term
| In intrinsic renal falure, what is the BUN/Creatine ratio, and why? |
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Definition
In intrinsic renal failure, the creatinine rises, but since there is no hypovolemia, the kidney does not respond by reabsorbing. Thus, the BUN/Creatinine ratio will be <20:1.
Thus, prerenal failure BUN/Cr <20:1. ; intrinsic renal failure BUN/Cr >20:1 |
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Term
| What would we expect to find in regards to urine sodium as related to prerenal failure? |
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Definition
| If sodium and water are being reabsorbed from the tubular fluid, the urine will be very concentrated, but have a low concentration of sodium (typically less than 20 mEq/L). |
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Term
| In contrast, in a kidney failing due to internal pathology, there is no hypovolemia, so the kidney is not trying to hold onto anything. Also, its ability to reabsorb is diminished and so it wastes both water and sodium. This leads to a dilute uring but an increased excretion of sodium in intrinsic renal failure. (typically greater than 40mEq/L) |
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Definition
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Term
| FENa what is it? What is the equation. |
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Definition
A more accurate clinical measurement of distinguishing prerenal vs. intrinsinc renal failure is FENa. This measures the percent of filtered sodium that gets excreted. FENa =fractional excretion of sodium
FENa = (amount of sodium excreted / amount of sodium filtered) x 100 |
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Term
| Prerenal failure FENa vs. Intrinsic renal failure |
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Definition
Prerenal <1%
Intrinsic >2% |
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Term
| In summary: Imagine the normal kidneys as a very selective sieve, keeping certain substances and excreting others. If the kidneys fail due to an internal problem (intrinsic renal failure, e.g. acute tubular necrosis), imagine that the sieve's holes are damaged so that they are not as selective as before. Water and sodium pour through and urine sodium concentration is high but urine is diulte. One could imagine that BUN is also spilling through the broken sieve as a way of remembering the lower BUN//CR Ration in intrinsic renal failure. |
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Definition
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Term
topic Postrenal failure:
What is hydroureter?
What is hydronephrosis? |
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Definition
hydroureter: dilation of ureter, proximal to site of an obstruction.
hydronephoris: Dilation of the renal pelvis due to backup from an obstruction. |
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Term
| What are the 2 types of glomeruli neropathies? |
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Definition
1. nephrotic syndrome
Leads to protein wasting in the urine.
Very often found in diabetic nephropathy.
2. nephritic syndrome
Often causes by strep |
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Term
| The ratio of BUN to creatinine is usually between |
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Definition
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