AKI

Question 1

Criteria for AKI

Answer 1

Rise in creatinine of ≥ 26 micromol/L in 48 hours

Rise in creatinine of ≥ 50% in 7 days

Urine output of < 0.5ml/kg/hour for > 6 hours

Question 2

Risk Facotors for AKI (8)

Answer 2

Consider possibility of aki in patients suffering with acute illness such as infection or having a surgical operation

Chronic kidney disease

Heart failure

Diabetes

Liver disease

Older age (above 65 years)

Cognitive impairment

Nephrotoxic medications such as NSAIDS and ACE inhibitors

Use of a contrast medium such as during CT scans

Question 3

Causes of AKI

Answer 3

Pre-renal Causes
Renal Causes
Post-renal Causes

Question 4

How does pre-renal AKI occur?

Answer 4

Inadequate blood supply to kidneys

May be due to:
Dehydration
Hypotension (shock)
Heart failure

Question 5

How does renal AKI occur?

Answer 5

Intrinsic disease in the kidney

May be due to:
Glomerulonephritis
Interstitial nephritis
Acute tubular necrosis

Question 6

How does post-renal AKI occur?

Answer 6

Caused by obstruction to the outflow of urine - obstructive uropathy

May be caused by:
Kidney stones
Masses such as cancer in the abdomen or pelvis
Ureter or uretral strictures
Enlarged prostate or prostate cancer

Question 7

Investigations for AKI

Answer 7

Urinalysis for protein, blood, leucocytes, nitrites and glucose

Leucocytes and nitrites suggest infection
Protein and blood suggest acute nephritis (but can be positive in infection)
Glucose suggests diabetes

Ultrasound of the urinary tract is used to look for obstruction

Question 8

Management of AKI

Answer 8

Correct the underlying cause:

Fluid rehydration with IV fluids in pre-renal AKI

Stop nephrotoxic medications such as NSAIDS and antihypertensives that reduce the filtration pressure (i.e. ACE inhibitors)

Relieve obstruction in a post-renal AKI

Question 9

Complications of AKI

Answer 9

Hyperkalaemia

Fluid overload, heart failure and pulmonary oedema

Metabolic acidosis

Uraemia (high urea) can lead to encephalopathy or pericarditis