1. Acute Kidney Injury / Acute Renal Failure

Question 1

Definition of AKI / ARF

Answer 1

Clinical term that covers a range of pathologies that cause Abrupt (acute) Renal Impariement

Evidenced by: Fall in GFR, Reduced UO, Increased Creatinine and Urea

Question 2

Prognosis of AKI / ARF

Answer 2

Almost always reversible if the cause is recognised early, treated appropriately, Avoid further Insults and Manage the consequences

Question 3

Most common clinical presentations for AKI / ARF?

Answer 3

Decreased Urine Output

Decreased GFR or Increased Urea / Creatinine on blood test

Question 4

Important to consider Physiological vs Pathological Causes for the Decreased Urine Output. What are Physiological causes of decreased urine output

Answer 4

When body conserves water - dehydration

Question 5

Describe the Classification of the possible Aetiologies for Acute Kidney Injury

Answer 5

1. Pre-renal
2. Renal
3. Post-renal

Question 6

Examples of Pre-renal Causes of AKI

Answer 6

Hypoperfusion of the kidney (causing ischaemia and damage) due to: Hypovolaemia and/or Relative Hypotension.

Due to:

• Blood Loss (haemorrhage)
• Fluid loss (diarrhoea, vomiting, oedema, sepsis)
• Reduced Cardiac Output (Heart Failure, Other cardiac events)
• Renovascular Obstruction (Atherosclerosis)

Question 7

Examples of Renal Causes of AKI

Answer 7

Chiefly due to interstitial damage, or involving the glomerulus and/or tubules

May be due to:

1. Nephrotoxins (Abx like gentamicin, radiographic contrast, myoglobin due to rhabdomyolysis, drug use, crush injury)
2. Glomerular Disease (e.g. glomerulonephritis)
3. Tubulointerstitial Nephritis (i.e. inflammation of mainly the interstitium rather than of mainly the glomeruli/nephrons) (due to Infection or Inflammation secondary to drugs, urate, Ca++)(Aetiologies include: Acute & Chronic Pyelonephritis, Acute Interstitial Nephritis, Analgesic Nephritis, NSAIDS)

Question 8

Typical Microscopic Features of Renal Diseases as a cause of AKI

For Acute vs Chronic

Answer 8

Interstitial, Glomerular or Tubular Involvement

Damage is usually associated with interstitial oedema
Leukocyte Infiltration - type depends on the cause

Acute: Focal Tubular Necrosis, Interstitial Oedema, Leukocyte Infiltration

Chronic: Predominant INterstitial Fibrosis, Leukocyte Infiltration

Question 9

Post-Renal Causes of AKI

Answer 9

Urinary Tract Obstruction

May be due to: prostatic enlargement in older men, tumours, renal calculi, post-surgery, urethral strictures, neurogenic

Main Feature of Post-Renal AKI: When the obstruction removed, the renal impairment should improve