Acute Kidney Injury

Question 1

What is acute kidney injury?

Answer 1

Acute drop in kidney function in <48hrs

Question 2

What are the 3 diagnostic criteria?

Answer 2

Rise in serum creatine of >/= 26.4 micromol/l in 48hrs
OR
50+% rise in serum creatine within 7 days
OR
A fall in urine output <0.5ml/kg/hr for 6+ hrs

Question 3

How are the causes of AKI split up?

Give 3 examples of each

What is the most common category of causes?

Answer 3

1. Pre-renal (due to inadequate blood supply)
   - Dehydration
   - Hypotension
   - Heart failure

Renal (due to intrinsic disease)

• Glomerulonephritis
• Interstitial nephritis
• Acute tubular necrosis (ATN)

Post-renal (obstruction to outflow)

• Kidney stones
• Masses in abdo/pelvis
• Ureter/urethral strictures
• Enlarged prostate/prostate cancer

Question 4

When would an USS be indicated?

Answer 4

To check for obstruction of urinary tract in suspected post-renal AKI

Question 5

What is the mnemonic to remember the nephrotoxic drugs that should be stopped in AKI?

Answer 5

DAMN

Diuretics
ACE/ARB
Metoformin
NSAIDS

(NB: ACEi are only causative in acute kidney injury - very useful for reducing proteinuria so used in other kidney conditions)

SPIRONOLACTONE AND GENTAMICIN

Question 6

What is the useful mnemonic for assessment and management?

Answer 6

RENAL DRS 26

Record baseline creatine (+regular U+E's)
Exclude obstruction (clinical/USS)
Nephrotoxic drugs stopped
Assess fluid status
Losses +/- catherisation

Dipstick (blood/protein)
Review meds
Screen (consider acute renal screen)

26 creatine rise for AKI diagnosis

Question 7

Why should an ECG be taken in a patient with AKI?

Answer 7

To check for hyperkalaemia

Peaked T wave

Question 8

What can result from a build up of urea due to poor GFR?

Answer 8

Uraemic complications e.g. encephalopathy + pericarditis

Question 9

What ABG is most likely in AKI?

Answer 9

Metabolic acidosis

due to lack of ammonia secretion - ammonia is an acid

Question 10

What is the most common cause of AKI?

Answer 10

Acute tubular necrosis

Destruction and damage of the tubular epithelial cells

Question 11

Muddy brown casts on urinalysis?

Answer 11

Acute tubular necrosis

Question 12

What type of AKI accounts for 1/4 of drug induced AKI?

Answer 12

Acute interstitial nephritis

Question 13

Rise in urea and creatine levels post new drug. Patient presents with fever and rash as well.

What is their urinalysis likely to show?
What condition is this?

Answer 13

Acute interstitial nephritis

Allergic picture

• increased WCC
• increased IgE
• increased eosinophils

Question 14

What kind of AKI can be caused by sepsis?

Answer 14

Acute tubular necrosis