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Renal failure Flashcards

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1
Q

How do you calculate FENa

A

FENa = 100(SCr x UNa)/(SNa x UCr)

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2
Q

What does the FENa measure?

A

tubular resorption of Na
FENa = (Na excreted/Na filtered)100

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3
Q

What does a FENa of < 1%, UNa < 20, Uosm > 500 indicate?

A

a pre-renal source (most common, 60%)

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4
Q

What does a FENa > 1% and a UNa > 40 indicate?

A

an intrinsic source of renal failure (35%)

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5
Q

What does a FENa > 4%, UNa > 40, and Uosm < 350 indicate?

A

a post-renal source of renal failure (5%)
-BPH
-bladder stones
-b/l ureteral obstruction
-neurogenic bladder

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6
Q

What are the KDIGO criteria stages of an AKI?

A

-1 = creatinine increase x1.5 - 1.9 or >/= 0.3mg/dL in 48hrs
UOP < 0.5mL/kg/hr for 6-12hrs
-2 = creat x2-2.9 baseline
UOP < 0.5 for >/= 12hrs
-3 = creat x3 baseline or >/= 4; initiation of RRT; or if < 18yrs a decrease in GFR to < 35
UOP < 0.3 for >/= 24hrs or anuria for >/= 12hrs

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7
Q

What is the definition of CKD?

A

persistent impairment of kidney function
-abnormally elevated serum creat for >3 months or GFR < 60mL

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8
Q

What GFR is associated w/ stage 4 CKD?

A

<15

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9
Q

What are some typical causes of ATN?

A

-prolonged pre-renal failure
-contrast nephropathy
-amioglycosides

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10
Q

What type of AKI has a BUN:creat of >20:1?

A

pre-renal

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11
Q

What type of AKI has a BUN:creat <10:1?

A

intrinsic

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12
Q

What type of AKI has a BUN:creat that is normal (10-20:1)?

A

post-renal

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13
Q

When is a FENa inacurate and a FeUrea should be used instead?

A

pts on diuretics d/t the increase in UNa d/t the diuretic

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14
Q

How do you calculate FEUrea?

A

FEUrea = 100(SCr x Uurea)/(Surea x UCr)

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15
Q

What does a FEUrea < 35% indicate?

A

prerenal cause of AKI

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16
Q

What does a FEUrea >50% indicate?

A

intrinsic cause of AKI

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17
Q

How does muscle mass influence creatinine?

A

low muscle mass can have a falsely low serum creatinine

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18
Q

What are cause of pre-renal ARF?

A

-hypovolemia
-decreased effective blood volume
-heart failure
-cirrhosis
-nephrotic syndrome
-renal vasoconstriction
-renal artery stenosis
-NSAIDs
-drug related: tacrolimus, cyclosporine
-hypercalcemia

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19
Q

What are the intrinsic renal causes of ARF?

A

-ATN
-AIN
-acute vascular syndromes
-intratubular obstruction
-intrarenal depositions (tumor-lysis syndrome)
-rhabdomyolitis
-glomerulonephritides

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20
Q

What type of infiltrate do you get w/ acute interstitial nephritis?

A

eosinophilic

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21
Q

What is the classic triad of acute intersitital nephritis?

A

-fever
-rash
-eosinophilia

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22
Q

Which medications hypersensitives can lead to acute interstitial nephritis?

A

-PCNs
-cephalosporins
-sulfa drugs
-diuretics
-anticonvulsants

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23
Q

What is seen on an UA of a pt w/ acute glomerulonephritis?

A

-hematuria
-RBC casts

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24
Q

How is acute glomerulonephritis dianosed?

A

renal bx

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25
What is the pathophysiology of acute tubular necrosis?
-oxidative injury to renal tubular epithelial cells -sloughing of cells into lumen -this creates an obstruction -tubular pressure increases -net filtration across glomerular capillaries decreases -GFR decreases
26
What are the ischemic causes of acute tubular necrosis?
-circulatory shock -sepsis -hypotension (for any reason) -hypoperfusion causing drugs (ACE-inhibitors, NSAIDs)
27
What are the nephrotoxic causes of acute tubular necrosis?
-drugs (aminoglycosides, amphotericin B, cisplatin) -radiocontrast dye -myoglobin
28
What part of the nephron is most susceptible to ischemia causing acute tubular necrosis?
loop of Henle
29
What is the definition of oliguria?
UOP < 400mL/day
30
What is the UOP of a patient w/ acute tubular necrosis?
can be oliguric or nonoliguric -nonoliguric can have a normal UOP or elevated up to 8L/day
31
What is the mortality of a patient w/ oliguric acute tubular necrosis?
60-90%
32
What is the mortality of a patient w/ nonoliguric acute tubular necrosis?
10 - 20%
33
What are some of the main complications seen w/ acute tubular necrosis?
-hyperkalemia -metabolic acidosis -electrolyte imbalance -excess total body water -malnutrition -abnormal drug metabolism -uremia
34
What are some sequela of AKI?
-hyperkalemia -often paired hypocalcemia and hyperphosphatemia -volume overload -metabolic acidosis
35
What are risk factors for developing an AKI in the ICU?
-age -CHF -liver failure -CKD -anemia -nephrotoxic exposures -infections/sepsis/shock -mechanical ventilation -surgery
36
What are non-AKI causes of increased BUN?
-rhabdo -increased protein ingestion -GI bleed -corticosteroid use
37
What is the RIFLE criteria for AKI?
-Risk = serum creat increase x1.5, GFR decrease > 25% UOP < 0.5 x6hr -Injury = serum creat increase x2, GFR decrease > 50% UOP < 0.5 x12hr -Failure = serum creat increase x3, serum creat >/= 4, GFR decr > 75%, UOP < 0.3 x24hr or anuria x12hr -Loss = persistent ARF defined as loss of kidney function > 4wks -ESKD = persists > 3 months
38
In the hospital setting what accounts for half of all cases of AKI?
hypoperfusion
39
What UNa, Uosm, and Usg is typical for prerenal AKI?
-UNa < 20 -Uosm > 500 -Usg > 1.015 (tubules reabsorb Na and water creating concentrated urine w/ low Na)
40
What does a UA significant for red cell casts indicate?
glomerulonephritis, vasculitis, trauma
41
What does a UA significant for heme pigmented casts indicate?
hemoglobinuria, myoglobinuria
42
What does a UA significant for leukocyte casts indicate?
pyelonephritis, papillary necrosis
43
What does a UA significant for renal tubular casts indicate?
ATN
44
What does a UA significant for "muddy" granular casts indicate?
ATN
45
What does a UA significant for leukocytes indicate?
URI, interstitial nephritis
46
What does a UA significant for eosinophils indicate?
acute interstitial nephritis (AIN)
47
What does a UA significant for crystals indicate?
urate, oxalate (ethylene glycol)
48
Which medications can cause ATN?
-aminoglycosides -amphotericin B -contrast -cyclosporine -platinum-based chemo -ACE inhibitors -NSAIDs
49
What pt factors make them more at risk for drug induced ATN?
-elderly -dehydrated -HTN -DM -those w/ mild underlying renal dysfunction -those w/ myeloma
50
How do aminoglycosides cause renal insufficiency?
by binding and injuring cellular proteins in proximal tubules
51
When should trough levels of aminoglycosides be drawn?
after 5.5 half lives when steady-state concentration has been acheived
52
Which type of contrast can be dialyzed off?
gadolinium, but it's still avoided in high-risk pts
53
How do NSAIDs cause kidney damage?
-prostaglandin E2 is a vasodilator that is pivotal in maintaining renal blood flow in pts w/ high renin/angiotensin states -NSAIDs block PGE2 formation and decrease renal blood flow -also encourage sodium, potassium, and fluid retention while inhibiting diuretic action
54
What electrolyte abnormalities are seen in rhabdo?
-rapidly increasing creatinine -disproportionate rise in K, phos, and uric acid
55
What electrolyte abnormalities are seen w/ tumor lysis syndrome?
-hyperkalemia -hyperphosphatemia -hypocalcemia -increased uric acid
56
Which medications are associated w/ the development of AIN?
-PCNs -cephalosporins -sulfonamides -quinolones -rifampin -thiazides -furosemide -NSAIDs -allopurinol -cimetidine
57
Which stain is needed to find urinary eosinophilia?
Hansel stain (urinary eosinophilia = AIN)
58
What are the major electrolyte disturbances of an AKI?
-hyperkalemia -hypermagnesemia (avoid antacids) -hyperphosphatemia -hyponatremia
59
Why do pts w/ AKI develop bleeding disorders?
inhibitory action of uremic toxins on PLTs and factor 8
60
Which factor is inhibited by uremia?
factor 8 -replace w/ DDAVP (an arginine vasopressor), FFP, cryo
61
Which minerals are lost through HD and should be replaced?
-folate -pyridoxine (B6)
62
What are the indications for HD/HF?
-fluid overload -refractory hyperkalemia or hypermagnesemia -symptomatic uremia (pericarditis, seizures, encephalopathy) -presence of a dialyzable toxin (salicylate, methanol, ethylene glycol)
63
What is the renal threshold when you start seeing myoglobin in the urine?
0.5 - 1.5mg/dL

Nephrology (3 decks)

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