Acute kidney injury

Question 1

AKI Staging: Urinary output

Answer 1

Normal: 0.5ml/kg/h
Non-Oliguric: > 500ml/day
Oliguric: < 500ml/day
Anuric (no urine): <50 ml/day

Question 2

AKI Staging: SCr

Answer 2

AKI if:
increase in SCr by >0.3 mg/dl within 48h
increase in SCr by 1.5x baseline occurred within 7 days

-UOP < 0.5 ml/kg/hr (less than optimal urine output) for 6 hours

Question 3

What is used to define the severity of AKI after AKI is diagnosed?

Answer 3

-RIFLE (change in renal function within 7 days)

-AKIN ((change in renal function within 48 hours)

(could be on the NAPLEX)

Question 4

RIFLE and AKIN

Answer 4

RIFLE
as the stage gets severe,
SCr: goes up (worse)
UOP: decreases
GFR: decreases

AKIN
SCr: goes up (worse
UOP: decreases

Question 5

Types of AKI

Answer 5

-Prerenal (70%)
-Intrinsic/Functional
-Postrenal/Obstructive

Question 6

Pathophysiology of Prerenal AKI

Answer 6

the kidneys are not being perfused appropriately (not enough blood perfusion)

-Volume depletion: insufficient water intake, diarrhea/vomiting, diarrhetic use, blood loss (decreased circulation)

-decreased circulation: low BP, blood loss,

-Functional: drug-related poor perfusion, ACEi, ARBs, NSAIDs

Question 7

Diagnosing prerenal AKI

Answer 7

-Urinalysis: specific gravity (concentrated urine) and urine sediments -> Hyaline casts

-Fe(Na): fractional excretion of sodium - impacted by diuretics - preventing Na from bein reabsorbed (higher amount in the urine) !! -> use Fe(urea) for patients who are on diuretics

Fe(Urea): fractional excretion

Question 8

What impacts the FeNa equation?

Answer 8

Diuretics
-use Fe(Urea)

Question 9

Fe(Na)
MEMORIZE

Answer 9

[U(Na)*SCr] / [U(Cr) * S(Na)] * 100
<1%, prerenal AKI
>2% potentially intrinsic AKI

Question 10

What Fe(Na) is expected in a patient who is not hydrated?

Answer 10

low Fe(Na), because the body try to prevent escaping of Na into the urine
Q: Prevention of Na filtration??? and how???
is the filtration of Na passive???

Question 11

Treatment of Prerenal AKI

Answer 11

Volume Depletion: fluid resuscitate (IV or oral fluid depending on the severity)

Decreased Circulation:
treat the cause: Hypotension due to heart failure or cirrhosis; Hypotension due to Sepsis, drug-induced hypotension (f.e. increased the dose of lisinopril to 40mg -> caused hypotension -> lower the dose back to 20mg

Functional: remove the offending agent if possible (if they really need ACEi or ARB make a risk/benefit assessment)

Question 12

Intrinsic AKI

Answer 12

Direct renal damage -> based on where the damage is: Tubular, Glomerular, Interstitial, Vascular

Question 13

Tubular AKI

Answer 13

Acute Tubular Necrosis (ATN) 85% of intrinsic AKI
can be ischemic: prolonged hypotension
can be drug-induced
-often fluid doesn’t help -> dialysis

Question 14

Glomerular AKI

Answer 14

Glomerulonephritis (often a complication of another disease)
-f.e. lupus nephritis
-Nephritic vs Nephrotic
-treat primary disease

Question 15

ATN vs AIN

Answer 15

ATN: direct damage to the kidney

AIN: allergic (immune) response

Question 16

What type of AKI is caused by Aminoglycosides?

Answer 16

ATN - direct damage

Question 17

What type of AKI is caused by nafcillin?

Answer 17

AIN

Question 18

Interstitial AKI

Answer 18

Acute Interstitial Nephritis (AIN)
-often inflammatory or allergic reaction of the kidneys
-often caused by drugs (PPI, antibiotics), infections, systemic disease
-> Stop the offending agent OR use steroids
-UA: eosinophiluria

Question 19

What might be elevated in interstitial AKI (allergic)?

Answer 19

eosinophils in the urine
-eosinophiluria

Question 20

Vascular AKI

Answer 20

-Renal embolic disease (embolism within the kidney)
-often treated like any other blood clot
-imaging to confirm diagnosis

Question 21

Drug-induced (ATN)

Answer 21

Acute tubular Necrosis
Aminoglycosides
Vancomycin
Amphotericin (antifungal)
Cisplatin (alkylating agent, chemo)
Contrast

Question 22

Drug-induced AIN

Answer 22

Acute Interstitial Nephritis (AIN)
Cephalosporin
Penicillins
NSAIDs
Diuretics
PPIs?

Question 23

Postrenal/Obstructive AKI
3rd cause of AKI

Answer 23

Obstruction of Urin Flow (urine cant leave the bladder -> back up of pressure -> renal damage)

Question 24

Types of Urine Flow Obstruction

Answer 24

-Bladder outlet (BPH)
-Urethral (could be a kind of cancer)
-Renal or Tubular (could be a kind of cancer)
-> Some drugs cause crystallization, bactrim and IV acyclovir
-> oral bactrim: counsel on sufficient fluid intake
-> IV acyclovir: need fluid IV when taking it

Question 25

Complications of AKI

Answer 25

-Hyperkalemia
-Acidosis
-Increased mortality
-longer length of stay in the hospital
-increased risk of progression to CKD/ESRD

Question 26

Are AKIs reversible

Answer 26

generally yes
-but loss of nephron cells with each AKI