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Flashcards in Acute Kidney Injury Deck (46)
1

What are three characteristics of renal failure (acute and chronic)?

impairment of gfr
elevation of BUN/creatinine
decreased GFR leads to accumulation of substances/drugs normally excreted by the kidney

2

What is the definition of AKI?

rapid deterioration of renal fxn (hours tod ays but less than 1 month)
greater than .5 mg/dl increase in serum creatinine or increase of 50% over baseline value
sometimes decreased urine output but not always
inability of kidney to regulate electrolytes/water

3

What is oliguria?

Anuria?

oliguria is decreased urine output below 400 ml/d

anuria is less than 100ml/day (almost none)

4

T of F:

1) AKI is usually symptomatic, discovered after pain

2) Most cases are irreversible if underlying disease is treated

1) False, most are asymptomatic and discovered in routine labe

2) False, most are reversible if underlying disease is treated

5

What are the three classifications of AKI?

Prerenal (55%)
Intrinsic Renal (40%)
Postrenal (5%)

6

What is preprenal ARF?

something before the kidneys is wrong, i.e. insufficient blood flow

7

What is intrinsic ARF?

something is damaged in the kidney

8

What is postrenal ARF?

something after the kidney, i.e. problem with bladder or ureter

9

What is found in the urine sediment of pts with prerenal ARF?

normal or few red blood cels or wbcs

10

In intrinsic ARF, what does one see in the urine sediment?

rbc casts, granular casts, eosinophils (primarily with allergic interstitial nephritis)

11

Tell if more characteristic of prerenal or intrinsic ARF:

Uosm: >500
Urine to plasma Osmolality: 20
Urine sediment: hyaline casts

Uosm>500 Prerenal
Intrin - 20 intrinsic
<10 prerenal

Hyaline casts - prerenal

12

What are things that can cause postrenal ARF?

prostate disease!!!!
cancer

13

What are symptoms associated with post-renal arf?

voiding complaints
may have distended bladder
u/a unremarkable
dx for ultrasound

14

What is the typically characteristic of the kidney on ultrasound during post-renal arf?

dilated calyxes

15

What is the key cause of prerenal arf?

additional causes?

volume depletion (gi, renal)

CHF
Shock from fluid losses, sepsis
hepatorenal syndrome
renal artery stenosis
NSAIDS

16

What do hyaline casts look like on UA (present in prerenal disorders)

they are clear, cylindrical rods

17

What does a Una less than 25 tell us about the type of ARF?

Una<25 = pre-renal (taking up all the na that it can)

18

Why is Uosm>500 in prerenal ARF?

all the vasopressin to fix volume depletion

19

What is hepatorenal syndrome?

Special case of prerenal AKI due to cirrhosis
Decreased BP despite increased ECFV
Kidneys intact and urinalysis normal (except Una)
worsening azotemia and progressive oliguria

20

Explain the pathway/pathology of HepatoRenal Syndrome (HRS)

portal htn
splanchnic vasodilation
decreased effective circulatory volume
activation of RAAS (leads to two things:
Na -> Ascites
Renal vasoconstriction -> HRS)

21

When is the only time you will see renal artery stenosis?

when it is bilateral. when only occurring on one side, the other kidney will compensate

22

What are two drug types that can lead to ARF in patients with renal artery stenosis?

Why?

ACEi and Angiotensin II blockers

Decreased levels of Angio II or blocking of it impairs renal auto--regulation (constrictino of efferent arterioles in RAS)

23

What are the two functions of Angiotensin II?

Aldosterone stimulation
Constriction of efferent arterioles

24

How do NSAIDs affect the kidneys?

they block prostaglandin synthesis, which dilate the afferent arterioles

25

What pts are at risk for ARF with NSAIDS?

true volume depletion
CHF
cirrhosis

- basically any time you have impaired blood flow due to volume

26

What are some intrinsic ARF of the glomerulus?

post-strep gn, lupus, rpgn, hepatitis, IgA nephro

27

What are intrinsic ARF involved with tubules?

ACUTE TUBULAR NECROSIS (due to prolonged HTN, meds)
Acute interstitial nephritis

28

What are intrinsic ARF causes involving the vasculature?

vasculitis

29

What can cause acute tubular necrosis?

ischemic injury (i.e. when prerenal continues too long)
toxic injury from radiocontrast or meds

30

Where does most ischemic injury occur?

in the proximal tubules and talh (where the most active transport needing 02 is occurring)

31

What are clinical clues of ATN?

muddy brown granular casts on UA
urina Na>20 (have aldo but dying tubules cannot absorb)

32

PRERENAL VS ATN

BUN/Crea >20:1

Prerenal

10-15:1 favors ATN

33

PRERENAL VS ATN

UA with granular casts

ATN

hyaline casts seen in prerenal

34

PRERENAL VS ATN


UNa+ <20 meq/L

Prerenal

>25 meq/L is in ATN because they cannot reabsorb the Na+

35

PRERENAL VS ATN


Uosm >500 mosm/kg

Prerenal

300-350 in ATN (isoosmotic because we cannot regulate it due to dying tubules

36

What causes the muddy brown casts in the UA of ATN?

dead cells coming out of body in urine

37

What causes the elevated BUN/Crea in ATN?

There is obstruction due to dead epithelial cells in the tubule, that dying, release Bun and crea and it goes back into bloodstream

38

What are drugs that can cause intrarenal AKI?

aminoglycosides, amphotericin B

39

What can cause acute interstitial nephritis (drugs)?

penicillins, cephalosporins, sulfonamides, NSAIDS

40

What percentage of people using aminoglycosides will have an increase in creatinine?

10-20% (more in urine)

41

Where does aminoglycoside accumulate in the kidney?

the proximal tubule cells

42

How does contrast nephropathy lead to AKI?

direct vasoconstrictive effects on arterioles and tubular toxicity

43

How can you avoid aKI in pts who need contrast imaging?

avoid volume depletion and nsaids and aCEI

44

What drugs typically cause acute interstitial nephritis?

antibiotics (penicillins B.lactams) NSAIDS

45

with mild dehydration, wil you have increased or decreased bp?

increased

46

in severe dehydration, increased or decreased bp? why?

decreased bp.

aldosterone is triggered, but there isn't enough h20 to increase bp