6. Acute Kidney Injury

Question 1

What is uraemia?

Answer 1

Term given to clinical symptoms which arise when nitrogenous metabolic waste products accumulate in blood, as a result of decreased filtration of these products by the kidneys

Question 2

What is AKI?

Answer 2

Deterioration of renal function occurring over hours or days
Urea ad creatinine rise rapidly
Usually associated with oliguria and usually reversible

Question 3

What are the dangerous consequences of AKI?

Answer 3

Volume overload, metabolic acidosis, hyperkalaemia

Question 4

Where can AKI take place?

Answer 4

Pre-renal - usually decreased blood flow
Intrinsic renal - usually direct damage to renal tissue
Post-renal - usually obstruction to flow of urine

Question 5

What are some pre-renal causes of AKI?

Answer 5

Reduced effective circulating volume - hypovolemia
Shock - septic, hypovolemic, cardiogenic
Renal artery stenosis or emboli
NSAIDs and ACE inhibitors - impair mechanisms of renal autoregulation so can predispose to AKI

Question 6

What are the intrinsic causes of AKI?

Answer 6

Acute tubular necrosis - ischaemia, rhabdomyolysis, drug toxicity, toxins
Acute interstitial nephritis - drugs, infections, hypercalcaemia
Glomerular disease - acute/rapidly progressive glomerulonephritis
Vascular disease - vasculitis, malignant hypertension

Question 7

What are some post-renal causes of AKI?

Answer 7

Bladder outflow obstruction - BPH, urethral strictures
Tumour - prostate, bladder, gynaecological malignancy
Stone
Retroperitoneal fibrosis caking ureteral obstruction

Question 8

What are the basic investigations of AKI?

Answer 8

Urine tests - dipstick, microscopy, culture, cytology
Blood tests and renal imaging
Additional serological tests can help clarify diagnosis

Question 9

What are the biochemical changes following AKI?

Answer 9

• Increase in plasma urea and creatinine conc
• Increase in plasma rate
• Increase in plasma conc of K+
• Metabolic acidosis and increase in anion gap
• Increase in plasma phosphate and decrease in plasma calcium
• Decrease in plasma Na+

Question 10

What is the management for AKI?

Answer 10

Depends on precipitating cause
Appropriate fluid replacement therapy always important to optimise blood flow to kidneys
Hypovolemia treated with fluids
Correct electrolyte disturbances - hyperkalaemia, acute uraemia
If obstruction - insert catheter or nephrostomy

Question 11

What are the signs and symptoms of AKI?

Answer 11

Dehydration
Decreased skin turgor 
Low JVP
Low BP
Weight loss

Question 12

What are the life-threatening complications of AKI?

Answer 12

Hyperkalaemia
Pulmonary oedema
Bleeding
- need urgent treatment