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Common acute kidney injury exam questions for medical finals, OSCEs and MRCP PACES

 

Question 1.

Define the terms acute kidney injury (AKI), oliguria and anuria

    • AKI: sudden deterioration in renal function leading to an inability to maintain fluid, electrolyte and acid-base balance
    • Oligura: reduced urine output; defined variously as <0.5 ml/kg/hour, <30 ml/hour or <400 ml/day
    • Anuria: complete absence of urine output

 

Question 2.

Outline the criteria for staging AKI

    • Stage 1: Cr ≥1.5-2 times baseline or urine output (UO) <0.5 ml/kg/hours for >6 consecutive hours
    • Stage 2: Cr ≥2-3 times baseline or UO <0.5 ml/kg/hours for >12 hours
    • Stage 3: Cr ≥3 times baseline or UO <0.3 ml/kg/h for ≥24 hours or anuria for >12 hours

 

Question 3.

List three broad categories of AKI

    • Pre-renal
    • Intrinsic renal
    • Post-renal

 

Question 4.

List four types of nephrotoxic drugs that you would stop/avoid

    • ACEIs
    • ARBs
    • NSAIDs
    • Aminoglycosides e.g. gentamicin

 

Question 5.

When assessing fluid status, what signs would you look for on examination that suggest a patient is hypovolaemic?

    • Cold, pale peripheries
    • Prolonged capillary refill times (CRT >2 s)
    • Decreased skin turgor
    • Reduced jugular venous pressure (JVP)
    • Sunken eyes
    • Dry lips, mouth and tongue
    • Tachycardia
    • Postural hypotension
    • Absolute hypotension
    • Dark urine

 

Question 6.

How can urinary & plasma osmolality and sodium help in determining the cause of AKI?

    • Pre-renal AKI: kidney is functioning maximally to retain salt and water; urinary osmolality is high (600-900 mosm/L) and urinary sodium is low (<10 mM)
    • ATN: kidney is functioning inadequately and is unable to retain salt and water; urinary osmolality approaches that of plasma(280 mosm/L) and urinary sodium rises (>30 mM)

Question 7.

Outline the possible complications of AKI

    • Hyperkalaemia
    • Hypo/hypernatraemia
    • Hypercalcaemia
    • Metabolic acidosis
    • Pulmonary oedema
    • Hypertension
    • Uraemic encephalopathy
    • Uraemic pericarditis

 

Question 8.

List the indications for commencing dialysis or filtration (CVVHF) in acute kidney injury

    • Urine output <0.3 ml/kg for 24 hours
    • Absolute anuria for >12 hours
    • Multi-organ failure
    • Refractory volume overload
    • Complications of uraemia
      • Uraemic encephalopathy
      • Uraemic pericarditis
    • Severe poisoning or drug overdose
    • Severe hypo/hyperthermia
    • Refractory hyperkalaemia >6.5 mM
    • Serum urea >27 mM
    • Refractory metabolic acidosis pH <7.15
    • Refractory electrolyte abnormalities
      • Hyponatraemia <115 mM
      • Hypernatraemia >165 mM
      • Hypercalcaemia