09.1 Acute Kidney Injury

Question 1

What criteria can be used to measure acute kidney injury?

Answer 1

KDIGO

AKIN, RIFLE

Question 2

What urine output is defined as oliguria?

Answer 2

Less than 500ml a day

Question 3

What urine output is classed as anuria?

Answer 3

Less than 100ml a day

Question 4

What are the three main causes of acute kidney injury?

Answer 4

Pre renal
Renal
Post renal

Question 5

What are the main causes of pre renal AKI?

Answer 5

1 - Reduced effective ECF volume (hypovolaemia, heart failure, distributive shock)
2 - Impaired renal autoregulation
2a - Preglomerular vasoconstriction (NSAIDs/sepsis)
2b - Postglomerular vasodilation (ACE inhibitors/AngII receptor antagonists)

Question 6

What can a reduce perfusion also lead to?

Answer 6

Acute tubular necrosis which itself is a cause of AKI.

Question 7

What are the main renal causes of AKI?

Answer 7

Renal artery/vein occlusion.
Acute tubular necrosis (ATN)
Glomerulonephritis (immune disease)
Intrarenal obstruction

Question 8

In ATN what tubules are usually damaged first?

Answer 8

PCT, as the DCT has a lower O2 demand.

Question 9

What are some endogenous causes of ATN?

Answer 9

Myoglobin
Urate
Bilirubin

Question 10

What are some exogenous causes of ATN?

Answer 10

Endotoxins
X Ray contrast
Drugs (ACEi, NSAIDs, aminoglycosides)
Poisons

Question 11

Name a primary cause of glomeruloneprhitis.

Answer 11

IgA nephropathy

Question 12

Name a systemic cause of glomeruloneprhitis.

Answer 12

SLE

Vasuculitis

Question 13

What are the main types of post renal causes of AKI?

Answer 13

Lumen blockage - e.g. stones
Within the wall blockage - e.g. stricture
Rise in pressure from the outside of a tube - e.g. Enlarged prostate/tumour

Question 14

What would you expect to see in the biochemistry of the serum of an AKI patient?

Answer 14

Increase Urea and Creatinine
Potential increased potassium and phosphate
Potential decreased calcium and sodium

Question 15

What must happen for a post renal obstruction to cause AKI?

Answer 15

Must block both kidneys or start with only one functioning kidney.

Question 16

When would you take a kidney biopsy?

Answer 16

After ruling out pre renal and post renal cause
Not confident in an ATN diagnosis
Systemic inflammatory markers are present

Question 17

How do you treat pre renal AKI?

Answer 17

Restore the volume

Fix the heart in the case of heart failure

Question 18

When would you initiate dialysis in renal caused AKI?

Answer 18

Can no longer secrete electrolytes, water or waste products

OR Acid base balance cannot be maintained

Question 19

How do you treat ATN?

Answer 19

Maintain perfusion and avoid nephrotoxins and let recover.

Question 20

How do you treat post renal AKI?

Answer 20

Urological intervention to remove obstruction

Question 21

What is acute kidney injury?

Answer 21

A decline in GFR that occurs during a period of less than 2 weeks. The decline is measured by an increase in serum creatinine.