Acute Kidney Injury

Question 1

How does acute kidney injury present

Answer 1

GI upset

Reduced consciousness level

Question 2

What history do AKI patients have?

Answer 2

Renal and cardiac history

Question 3

What constitutes AKI?

Answer 3

> = 26 mmol/L rise in creatinine over 48 hours
=50% rise in creatinine in past 7 days
<=0.5ml/kg/hr output in past 6 hours

Question 4

How can urinalysis help identify the cause of AKI?

Answer 4

Intra-renal
Leucocytes and nitrites suggest infection
Protein and blood suggest acute nephritis
If negative: Pre-renal

Question 5

How can you differentiate between pre-renal and intra-renal causes of AKI?

Answer 5

Pre-renal: Inadequate blood supply

Intra-renal: Intrinsic disease

Question 6

How can you differentiate between intra-renal and post-renal causes of AKI?

Answer 6

Intra-renal: intrinsic disease (eg nephritis, ATN)

Post-renal: outflow obstruction (kidney stones, masses)

Question 7

How do you initally manage AKI?

Answer 7

Medication review
Monitor fluids
Fluid therapy if pre-renal cause

Question 8

What meds should be stopped due to worsening renal function?

Answer 8

NSAIDs (except low dose aspirin)
Aminoglycosides (mycins)
ACE inhibitors
ARBs
Diuretics

Question 9

What 3 meds may be stopped due to how they worsen toxicity in AKI?

Answer 9

Metformin
Lithium
Digoxin

Question 10

What is the role of loop diuretics in AKI?

Answer 10

Not routinely recommended

Can help if there is fluid overload

Question 11

In suspected AKI, when would you discuss…
With a general physician
With a nephrologist within 24 hrs

Answer 11

General: Stage 1 + uncertainty
Neph: 4/5 CKD, specialist management needed, renal transplant

Question 12

When would you refer same day/admit

Answer 12

AKI 3
Obstruction
Acute deterioration/sepsis

Question 13

In terms of creatinine and urine output what is Stage 1-3 AKI

Answer 13

Stage 1
>=26 mmol/L increase in 48hrs / 50-99% increase in 7 days
<0.5ml/kg/hr for 6 hours
Stage 2
100-199% increase in 7 days
<0.5ml/kg/hr for 12 hours
Stage 3
200% increase in 7 days
<0.3ml/kg/hr for 12 hours

Question 14

What 3 circumstances require nephrology follow up for AKI?

Answer 14

Previous episodes
Established CKD
eGFR falls below 30 during monitoring

Question 15

AKI + hypertension with associated fever.
Following admin of antibiotics or NSAIDs
Increased eosinophils are present.
This indicates what?

Answer 15

Acute interstitial nephritis

Question 16

How do you treat acute interstitial nephritis?

Answer 16

Steroids for inflammation

Question 17

How can acute tubular necrosis and interstitial nephritis be distinguished in urine?

Answer 17

ATN: Muddy casts
IKD: white casts

Question 18

How can pre-renal uraemia and acute tubular necrosis be differentiated in terms of
Urine sodium
Urine osmolality
Serum urea/creatinine ratio
Fluid challenge response
Urine appearance

Answer 18

Pre-renal uraemia // acute tubular necrosis

low (want to retain salt to keep water)  // high
High (retaining water // low
Raised // normal
Good (helps with low volume) // poor
'bland' // brown casts