Renal - AKI

Question 1

How is AKI diagnosed?

Answer 1

Serum creatinine or urine output

Question 2

What are the NICE guidelines for diagnosis of an AKI?

Answer 2

• Rise in creatinine of more than 25 micromol/L in 48 hours
• Rise in creatinine of more than 50% in 7 days
• Urine output of less than 0.5ml/kg/hour for 6 hours

Question 3

What are the risk factors to developing AKI?

Answer 3

• Age
• Sepsis
• CKD
• HF
• Diabetes
• Liver disease
• Contrast
• Medications (NSAIDs, gentamicin, diuretics, ACEi)

Question 4

What are the pre-renal causes of AKI?

Answer 4

Hypoperfusion issue

Dehydration
Shock
HF

Question 5

What are the renal causes of AKI?

Answer 5

Intrinsic disease
- Acute tubular necrosis
- Glomerulonephritis
- Acute interstitial nephritis
- Rhabdomyolysis
- Haemolytic uraemic syndrome

Question 6

What are the post-renal causes of AKI?

Answer 6

Obstructive- URINARY RETENTION
- Kidney stones
- Tumours
- Urethral strictures
- BPH
- Neurogenic bladder

Question 7

What is acute tubular necrosis and what causes it?

Answer 7

Necrosis of the epithelial cells of renal tubules

Most common cause of AKI

Due to:
- Ischaemia
- Nephrotoxins (gentamicin, contrast or cisplatin)

Question 8

How can acute tubular necrosis be confirmed?

Answer 8

Muddy brown casts on urinalysis

Renal tubular epithelial cells can also be seen

Question 9

How long does it take to recover from acute tubular necrosis?

Answer 9

1-3 weeks

Epithelial cells regenerate

Question 10

How are AKIs managed?

Answer 10

Prevention
- Avoid nephrotoxic medication where possible
- Ensure adequate fluid intake
- Fluids before and after contrast

Treatment
- IV fluids- dehydration and hypovolaemia
- Withhold medications that worsen AKI (NSAIDs, ARBs and ACEi)
- Adjust medication that can accumulate in reduced renal function (metformin and opioids)
- Relieve obstruction
- Dialysis in severe cases

Question 11

What is done for an unexplained AKI?

Answer 11

USS KUB

No obvious cause, look for structural reasons

Question 12

Why do ACEi cause a rise in creatinine?

Answer 12

ACEi lead to vasodilation of the efferent and afferent arterioles of the glomeruli which reduces glomerular hypertension .

Reducing glomerular filtration pressure means less creatinine is filtered and excreted from the kidneys, causing creatinine levels to rise.

Question 13

What are the NICE guidelines for starting an ACEi in relation to creatinine levels?

Answer 13

Should be stopped if creatinine rises to more than 30% of baseline

Question 14

What are the complications of AKI?

Answer 14

Fluid overload, HF and pulmonary oedema
- Hyperkalaemia
- Metabolic acidosis
- Uraemia- can lead to encephalopathy and pericarditis

Question 15

How are AKIs staged?

Answer 15

Question 16

How should metabolic acidosis be treated?

Answer 16

First line
IV 0.9% NaCl

Second line
IV Sodium bicarbonate

Question 17

What is a uraemic tinge?

Answer 17

Brown-grey colour to the skin

Question 18

What causes a uraemic tinge?

Answer 18

Urea

Build-up of urea due to overproduction e.g. GI bleed or decreased excretion e.g AKI, dehydration