Acute Kidney Injury

Question 1

Lab definition of AKI

Answer 1

1) SCr bump by 0.3 mg/dL
2) Scr bump by 50%
3) UOP <0.5mL/kg.hr

Question 2

Stage I AKI

Answer 2

1.0- to 1.5-fold increase in SCr, or decline in UOP to 0.5 mL/kg/h over 6–12 hours

Question 3

Stage II AKI

Answer 3

2.0- to 2.9-fold increase in SCr or decline in UOP to 0.5 mL/kg/h over 12 hours or longer

Question 4

Stage III AKI

Answer 4

3-fold or greater increase in SCr or decline in UOP to less than 0.3 mL/kg/h for 24 hours or longer or anuria for 12 hours or longer

Question 5

Signs and sxs of AKI due to ____, or underlying.

Answer 5

1. Uremia - N/V, malaise, altered sensorium, +/- asterixsi
2. HTN, fluidoverload
3. Pericardial effusion/tamponade +/- friction rub
4. Arrhythmia (hyperkalemia)
5. Coagulopathy - platelet dysfunction from uremia

Question 6

Lab findings in AKI

Answer 6

BMP - high SCr, BUN, K
Ph - high
AG and non-gap metabolic acidosis

Question 7

Categories of AKI

Answer 7

1. pre-renal
2. intrinsic
3. post-renal

Question 8

Pre-renal causes of AKI

Answer 8

1. Poor renal perfusion – hypovolemia, decreased cardiac output, systemic vasodilation (sepsis), acute/chronic anemia, burns, GI losses, overdiuresis
2. Renal vasoconstriction - NSAIDS, ACEi/ARBs, contrast, calcineurin inhibitors, HRS, hyperCa
3. Large vessel - RAS, vasculitis, dissection, abd compartment syndrome, renal venous congestion, VTE

Question 9

Urinalysysis in pre-renal

Answer 9

1. Bland sediment, hyaline casts (nonspecific)
2. FeNa <1%
3. UNa <20
4. Uosm >500
5. BUN:Cr >20

Question 10

Post-renal causes of AKI

Answer 10

1. urethral obstruction, bladder dysfunction/obstruction, ureteral obstruction, BPH, anticholinergic meds, malignancy to bladder/prostate/cervix, retroperitoneal fibrosis, neurogenic bladder
2. Less common: blood clots, bilateral ureteral stones, urethral stones/stricture, bilaterally papillary necrosis

Question 11

Urinalysis in post-renal

Answer 11

1. May appear to be prerenal at first

2. Bland sediment, variable FeNa

Question 12

Intrinsic causes of AKI

Answer 12

1. Acute Tubular Necrosis
2. Acute Interstitial nephritis
3. Small-med vasculitis
4. Glomerulonephritis

Question 13

Etiologies of ATN

Answer 13

1. Ischemia - progression on inadequately treated prerenal
2. Toxins
3. Contrast-induced

Question 14

Common toxins leading to ATN

Answer 14

aminoglycosides, amphotericin B, cisplatin, HES

Question 15

What two preexisting conditions predispose a patient the greatest for CIAKI (contrast-induced AKI)

Answer 15

Renal insufficiency (SCr >2.0 and DM)

Question 16

Timeline of CIAKI

Answer 16

1. AKI within 24-48 hours after the radiocontrast study
2. Peak 3-5 days
3. Resolves 7-10 days

Question 17

Lab work-up in ATN

Answer 17

BMP: hyperkalemia, BUN:Cr <20:1
Ph elevated
FeNa >2%
UA: muddy brown casts

Question 18

Three phases of ATN

Answer 18

1. Initial injury
2. Maintenance - oliguric vs nonoliguric, 1-3 weeks to several months of cellular repair and removal of tubular debris
3. Recovery - heralded by diuresis

Question 19

Signs / sxs of AIN

Answer 19

Fever
Transient maculopapular rash
Pyuria with eosinophilia, WBC casts, hematuria