Acute kidney injury (AKI)

Question 1

Define acute kidney injury

Answer 1

Abrupt loss of kidney function resulting in retention of urea & other nitrogenous waste products & the dysregulation of extracellular volume & electrolytes

Question 2

KDIGO classification of AKI

3

Answer 2

Increase in serum creatinine >26 micro mol/L within 48hrs
Increase in serum creatinine >1.5 times baseline within preceding 7 days
Urine volume <0.5 ml/kg/hr for 6 hrs

Question 3

Location of cause of AKI & reason

3

Answer 3

Pre renal - due to inadequate perfusion
Intrinsic renal - intrinsic/due to cellular damage
Post renal - due to obstruction

Question 4

Aetiology of AKI - pre renal

general + 6

Answer 4

Due to inadequate perfusion

Hypovolaemia
Heart failure
Cirrhosis
Nephrotic syndrome
Hypotension
Renal hypoperfusion

Question 5

Aetiology of AKI - intrinsic renal

general + 5

Answer 5

Intrinsic/due to cellular damage

Glomerular - glomerulonephritis, haemolytic uraemia syndrome
Tubular - ace tubular necrosis
Interstitial - acute interstitial nephritis
Vasculitides - e.g. Wegener’s granulomatosis
Eclampsia

Question 6

Aetiology of AKI - post renal

general + 4

Answer 6

Due to obstruction

Calculi
Urethral stricture
Prostatic hypertrophy or malignancy
Bladder tumour

Question 7

Risk factors for AKI

8

Answer 7

Age
CKD
Comorbidities (e.g. heart failure)
Sepsis
Hypovolaemia
Use of nephrotoxic medications
Emergency surgery
Diabetes mellitus

Question 8

Epidemiology of AKI

prevalence, age

Answer 8

15% adults admitted to hospital will develop AKI

Most common in the ELDERLY

Question 9

Presenting symptoms of AKI

general + 4

Answer 9

Depends on underlying cause

Oliguria/anuria
N&V
Dehydration
Confusion

Question 10

Signs of AKI on physical examination

5

Answer 10

Hypertension
Distended bladder
Dehydration - postural hypotension
Fluid overload - raised JVP , pulmonary & peripheral oedema
Pallor, rash, bruising

Question 11

Investigations for AKI

3

Answer 11

Urinalysis
Bloods
Imaging

Question 12

Investigations for AKI - urinalysis

5

Answer 12

Blood - suggests nephritic cause
Leucocyte esterase & nitrites - UTI
Glucose
Protein
Urine osmolality

Question 13

Investigations for AKI - bloods

7

Answer 13

FBC
Blood film
U&Es
Clotting
CRP
Immunology
Virology - check for hepatitis & HIV

Question 14

Immunology investigations for AKI

5

Answer 14

Serum immunoglobulins & protein electrophoresis
ANA
complement levels
anti-GBM antibodies
antistreptolysin-O antibodies

Question 15

Investigations for AKI - imaging

main +2

Answer 15

Ultrasound 
check for post renal cause 
look for hydronephrosis 
CXR - pulmonary oedema
AXR - renal stones

Question 16

Management of AKI - 4 main components

Answer 16

1) Protect patient from hyperkalaemia
2) Optimise fluid balance
3) Stop nephrotoxic drugs
4) Consider for dialysis

Question 17

Management of AKI - general

5

Answer 17

Treat the cause
Monitor serum creatinine, sodium, potassium, calcium, phosphate & glucose
Identify & treat infection
Urgent relief of urinary tract obstruction
Refer to nephrology if intrinsic renal disease is suspected

Question 18

Reasons to consider renal replacement therapy (RRT)

4

Answer 18

Hyperkalaemia refractory to medical management
Pulmonary oedema refractory to medical management
Severe metabolic acidaemia
Uraemic complications

Question 19

Complications of AKI

5

Answer 19

Pulmonary oedema
Acidaemia
Uraemia 
Hyperkalaemia
Bleeding

Question 20

Prognosis for AKI

2 general + 5 indicators for poor prognosis

Answer 20

Inpatient mortality varies depending on cause & comorbidities
Increased risk of developing CKD

Indicators of poor prognosis:
Age
Multiple organ failure 
Oliguria
Hypertension
CKD