kidney- acute renal failure

Question 1

what is the hallmark of acute renal failure? what lab values go along with this?

Answer 1

azotemia

increased BUN and creatinine

Question 2

what are the 3 divisions of acute renal failure?

Answer 2

pre-renal
intra-renal
post-renal

Question 3

what is the serum BUN:Cr ratio in pre renal azotemia? FeNa? serum osmolarity?

Answer 3

BUN:CR >15

FeNa 500 mOsm/kg

Question 4

what is the serum BUN:Cr ratio in the early stages of post renal azotemia? FeNa? serum osmolarity?

Answer 4

BUN:CR >15

FeNa 500 mOsm/kg

Question 5

what is the serum BUN:Cr ratio in acute tubular necrosis? FeNa? serum osmolarity?

Answer 5

BUN:CR 2%

urine osm <500 mOsm/kg

Question 6

what results from long standing post renal azotemia?

Answer 6

obstruction leads to tubular damage which results in:
BUN:CR 2
urine osm <500 mOsm/kg

Question 7

what FeNa value indicates an intact tubular function?

Answer 7

FeNa <1%

Question 8

what are the 2 etiologies of acute tubular necrosis?

Answer 8

ischemic or necrotic

Question 9

what is the usual cause of ischemic acute tubular necrosis

Answer 9

due to decreased blood supply usually preceded by pre renal azotemia

Question 10

what 2 locations in the kidney are particularly susceptible to ischemic acute tubular necrosis?

Answer 10

proximal tubule and medullary segment of the thick ascending limb

Question 11

what location in the kidney is particularly susceptible to nephrotoxic acute tubular necrosis?

Answer 11

proximal tubule

Question 12

what is the most common cause of nephrotoxic acute tubular necrosis?

Answer 12

aminoglycosides

Question 13

if you have nephrotoxic acute tubular necrosis and you see oxalate crystals in the urine, what do you think the patient ingested?

Answer 13

ethylene glycol

Question 14

what 2 prophylactic measures are used prior to chemotherapy to decrease the risk of urate induce acute tubular necrosis (nephrotic ATN)

Answer 14

hydration and allopurinol

Question 15

list the clinical features associated with acute tubular necrosis (whats in the urine, what electrolyte is high/low)

Answer 15

oliguria with brown, granular casts
elevated BUN and creatinine
hyperkalemia (due to decreased renal excretion) with metabolic acidosis

Question 16

what are 3 drugs that can cause acute interstitial nephritis?

Answer 16

NSAIDs
penicillin
diuretics

Question 17

how does acute interstitial nephritis present?

Answer 17

oliguria, fever, rash (days to weeks after starting medication)
eosinophils can be seen in the urine
leukocyte casts may be present

Question 18

what can acute interstitial nephritis lead to?

Answer 18

renal papillary necrosis

Question 19

If acute renal necrosis is caused by myoglobinuria or hemoglobinuria, what is the distinct pathological finding?

Answer 19

red casts

Question 20

What is the mnemonic for the causes of renal papillary necrosis?

Answer 20

POSTCARDS

P - pyelonephritis
O - obstruction
S - sickle cell
T - TB
C - chronic liver disease
A - analgesic abuse
R - renal transplant rejection
D - diabetes
S - systemic vasculitis

Question 21

What usually causes HUS?

Answer 21

ecoli toxin in children from hamburgers or petting zoos

Question 22

What are the pathognomonic findings in HUS?

Answer 22

shistocytes, thrombocytopenia and hemolytic anemia, rapidly progressive renal failure