Acute kidney injury Flashcards Preview

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Flashcards in Acute kidney injury Deck (36):
1

definition: acute kidney injury

reduction in glomerular filtration rate resulting in azotemia developing over a few times

2

acute kidney injury is commonly due to __________-

renal ischemia or toxins

3

is AKI reversible or irreversible?

reversible

4

diagnostic criteria for AKI

- absolute increase in serum creatinine level of 0.3 mg/dL or more
- over 50% increase in serum creatinine
- reduction of urine output less than 500 mL in 24 hr

5

definition: azotemia

elevation of nitrogenous waste products related to insufficient filtering of blood by the kidneys

6

definition: oliguria

less than 400-500 mL / day

7

definition: anuria

less than 50 mL / day

8

what is the key test to understanding what is going on with the kidney?

UA

9

creatinine clearance can be used to estimate _____

GFR

10

serum creatinine levels are inversely proportional to _____

GFR

11

creatinine clearance _________ (underestimates / overestimates) GFR

overestimates

12

BUN is a less accurate indicator of GFR than creatinine due to variation in what 3 factors?

- protein intake
- catabolic rate
- tubular reabsorption

13

what is the cause of urine casts?

trapping of cellular elements in a matrix of protein secreted by renal tubule cells

14

what type of casts are seen in acute tubular necrosis? what is the appearance of the urine?

- granular casts
- "muddy brown" urine

15

- age
- NSAIDs
- CKD

these affect which glomerular arteriole? how?

afferent (prevent dilation)

16

- ACE inhibitors
- ARBs

these affect which glomerular arteriole? how?

efferent (prevent angiotensin II mediated vasoconstriction)

17

what are the three types of AKI?

- pre-renal
- renal
- post-renal

18

what is the etiology of pre-renal AKI? what is one major condition associated with it?

- impaired effective renal perfusion

- volume depletion

19

what is the etiology of renal AKI? what is one major condition associated with it?

- intrinsic renal disease (glomerular, tubular, interstitial, vascular)

- acute tubular necrosis

20

what is the etiology of post-renal AKI? what is one major condition associated with it?

- obstruction of urinary flow

- BPH, tumor

21

prerenal AKI has decreased GFR ________ (with / without) ischemic or nephrotoxic injury to tubules

without

22

what is the BUN : creatinine ratio for prerenal AKI?

over 20 : 1

23

what type of casts can be seen in prerenal (volume depleted) AKI?

hyaline

24

what is the most common cause of renal AKI?

acute tubular necrosis (ATN)

25

what are the morphologic features of ATN?

- tubular dilation
- attenuation of tubular epithelium
- loss of epithelial cell brush border
- granular cast material
- mitotic figures

26

can tubule cells regenerate following ATN?

yes

27

what is obstructive uropathy?

obstruction of the urinary tract at any level that affects both kidneys

28

what should be ruled out in all patients with oliguria?

obstructive uropathy (post-renal AKI)

29

what is hydronephrosis?

distension and dilation of the renal pelvis calyces

30

what test is used to differentiate prerenal AKI from ATN?

assessment of urine sodium excretion

31

what test do you use to exclude postrenal AKI?

renal imaging (US, CT)

32

how is fractional excretion of sodium expressed?

amount of sodium excreted over amount of sodium filtered by glomeruli

33

in the setting of volume depletion, urine Na reabsorption should be _________ (increased / decreased) in the proximal tubules

what would the FENa be?

- increased

- FENa less than 1%

34

if the proximal tubules are injured via ATN, how is sodium handling affected? what is the FENa result?

- reabsorption will be impaired?

- FENa over 2%

35

what lab helps to differentiate between prerenal azotemia and ATN?

FENa

36

what is the FENa level in ATN? prerenal azotemia?

- ATN: over 2%

- prerenal azotemia: less than 1%