AKI

Question 1

Define AKI.

Answer 1

An acute decline in kidney function, measured using serum creatinine.

Question 2

Define the criteria for AKI.

Answer 2

• Rise in creatinine of ≥25 micromol/L in 48 hours
• Rise in creatinine of ≥50% in 7 days
• Urine output of <0.5ml/kg/hour for >6 hours

Question 3

What are some of the risk factors for AKI?

Answer 3

• Infection
• Surgery
• CKD
• HF
• Diabetes
• Older age (above 65 years)
• Cognitive impairment
• Nephrotoxic medications
• Contrast medium

Question 4

How are the causes of AKI subdivided?

Answer 4

• Pre-renal
• Renal
• Post-renal

Question 5

Which type of causes are most common in AKI?

Answer 5

Pre-renal

Question 6

How do pre-renal causes give rise to AKI?

Answer 6

They all cause hypoperfusion of the kidneys, leading to poor blood filtration.

Question 7

Name the pre-renal causes of AKI.

Answer 7

• Shock (sepsis, anaphylaxis etc.)
• Dehydration
• HF

Question 8

How do renal causes give rise to AKI?

Answer 8

Intrinsic disease of the kidney impairs its filtration.

Question 9

Name the renal causes of AKI.

Answer 9

• Glomerulonephritis
• Interstitial nephritis
• Acute tubular necrosis (medications/nephrotoxins)

Question 10

How do post-renal causes give rise to AKI?

Answer 10

Cause an outflow obstruction causing back-pressure into the kidney and reduced kidney function. This is called an obstructive uropathy.

Question 11

Name the post-renal causes of AKI.

Answer 11

Obstruction

• Calculi
• Stricture e.g. urethral or ureteric
• Prostate (BPH or Ca)
• Abdo/Pelvic masses

Question 12

What bedside test is important?

Answer 12

Urine dip

• Nitrites/Leukocytes (Infection)
• Haematuria (Malignancy/Nephritis)
• Proteinuria (Nephritis)
• Glucose (Diabetes)

Question 13

What imaging is useful?

Answer 13

US KUB- for an obstruction if another cause isn’t found

Question 14

How can AKI be prevented?

Answer 14

• Avoid nephrotoxins e.g. NSAIDs and ACEi

- Fluid hydration (Oral and IV if needed)

Question 15

How is AKI medically treated?

Answer 15

• Pre-renal (hydration)
• Renal (remove nephrotoxins, treat intrinsic disease)
• Post-renal (relieve the obstruction e.g. TURP)

Question 16

What are the complications of AKI?

Answer 16

• Hyperkalaemia
• Fluid overload, heart failure and pulmonary oedema
• Metabolic acidosis
• Uraemia (high urea) can lead to encephalopathy, pericarditis and gout

Question 17

How many stages of AKI are there?

Answer 17

3

Question 18

Describe stage 1 AKI.

Answer 18

Creatinine rise of 26 micromol or more within 48 hours OR

Creatinine rise of 50–99% from baseline within 7 days (1.50–1.99 x baseline) OR

Urine output < 0.5 mL/kg/h for more than 6 hours

Question 19

Describe stage 2 AKI.

Answer 19

100–199% creatinine rise from baseline within 7 days (2.00–2.99 x baseline) OR

Urine output < 0.5 mL/kg/hour for more than 12 hours

Question 20

Describe stage 3 AKI.

Answer 20

200% or more creatinine rise from baseline within 7 days* (3.00 or more x baseline) OR

Creatinine rise to 354 micromol/L or more with acute rise of 26 micromol/L or more within 48 hours or 50% or more rise within 7 days OR

Urine output < 0.3 mL/kg/hour for 24 hours or anuria for 12 hours