Acute Renal Failure

Question 1

3 Lab Values of Pre-renal Azotemia

Answer 1

BUN:Cr ratio above 15 (with high renin)

Tubular function remains intact so FENa below 1% and osmolarity greater than 500 mOsm/kg

Question 2

Postrenal Azotemia 3 Lab Values Early and Long-Standing

Answer 2

BUN:Cr > 15, FENa below 1% and osm greater than 500
Long standing, tubules get damaged, so
BUN:Cr less than 15, FENa above 2%, urine osm <500

Question 3

Acute Tubular Necrosis (what it is, 3 lab values, findings in urine)

Answer 3

Injury and necrosis of tubular cells causes them to fall off and plug tubules
BUN:Cr less than 15, FENa above 2%, urine osm <500
Brown, granular casts seen in urine

Question 4

2 Regions Susceptible to Ischemic ATN

Answer 4

PT and medullary segment of TALH

Question 5

Nephrotoxic ATN (location, most common cause, other lab finding)

Answer 5

PT
Aminoglycosides
Hyperkalemia due to decreased renal excretion, with metabolic acidosis (increased AG bc decreased excretion of organic acids)

Question 6

Acute Interstitial Nephritis (what it is, 3 common causes, presentation including hallmark urine finding)

Answer 6

Drug-induced hypersensitivity reaction of interstitium that can spread to tubules
NSAIDs, penicillins, and diuretics
Presents as oliguria w/ rash/fever and EOSINOPHILS in urine

Question 7

Renal Papillary Necrosis (presentation and common cause)

Answer 7

Gross hematuria and flank pain

Chronic analgesic abuse (long term phenacetin or aspirin)