Urinary 12 - AKI

Question 1

List the 3 possible findings in AKI:

Answer 1

1) Increased serum Creatinine by > 26.5uM in 48hrs
2) Increased serum Creatinine by > 1.5x baseline within 7 days
3) Urine volume < 0.5 ml/kg/hr for 6 hrs

Question 2

Define AKI:

Answer 2

Decline in GFR over days/weeks, upsetting ECF volume, electrolyte and acid-base homeostasis, and causing accumulation of nitrogenous waste products

Question 3

The causes of AKI are split into which 3 categories?

Answer 3

1) Pre-Renal
2) Intrinsic Renal
3) Post-Renal

Question 4

How do heart failure, sepsis, cirrhosis and anaphylaxis all cause AKI?

Answer 4

Decreased ECF volume = Decreased renal perfusion

Question 5

How do NSAIDs, ACEi and AIIR antagonists cause AKI?

Answer 5

Impair renal autoregulation pathways = cannot increase renal perfusion

Question 6

If pre-renal AKI is not rapidly treated, what will it develop into? Why?

Answer 6

ATN - Acute Tubular Necrosis
Inadequate perfusion = ischaemic cell damage
Drug OD = nephrotoxic cell damage

Question 7

What are the 2 types of Acute Tubular Necrosis (ATN)?

Answer 7

1) Ischaemic

2) Nephrotoxic

Question 8

What parts of the kidney is most susceptible to ischaemia?

Answer 8

Proximal tubule (part. S3 segment)
Thick Ascending Limb of LoH (TAL)

Question 9

Give 5 causes of nephrotoxic ATN (acute nephrotoxic necrosis):

Answer 9

1) Myoglobin
2) Poisons
3) Drugs
4) Bilirubin
5) Urate

Question 10

Why may an elderly person develop nephrotoxic ATN after prolonged immobilisation?

Answer 10

Prolonged immobilisation causes rhabdomyolysis

Myoglobin is toxic to tubular cells, and may obstruct tubule = necrosis

Question 11

Name 5 intrinsic renal diseases leading to AKI:

Answer 11

1) Acute Tubular Necrosis (ATN)
2) Glomerulonephritis - IgA nephropathy, SLE
3) Small vessel disease - Haemolytic anaemia
4) Acute Tubulo-Interstitial Nephritis - Infection/toxin-induced
5) Renal artery/vein occlusion

Question 12

Describe post-renal causes of AKI:

Answer 12

1) Obstruction within lumen
2) Obstruction within wall
3) External compression
Must affect both kidneys

Question 13

What serum findings are ALWAYS found in AKI?

Answer 13

Raised Creatinine

Raised Urea

Question 14

What ECG changes are associated with raised serum K+?

Answer 14

• Tall T waves
• Small/absent P waves
• Increased P-R interval

Question 15

What changes to ECF [K+] typically occurs in AKI?

Answer 15

Raised ECF [K+]

Question 16

What signs of underperfusion can you check for externally?

Answer 16

• Cool peripheries
• Increased pulse
• Decreased BP/postural hypotension
• Decreased skin turgor

Question 17

If dipstick test shows ^ proteinuria and ^ haematuria, what is the most likely cause of the AKI?

Answer 17

Glomerulonephritis (intrinsic renal)

Question 18

Which investigations would be carried out if suspected glomerulonephritis, and what would the findings be?

Answer 18

Urinalysis: Proteinuria + Haematuria
Urine microscopy: RBC casts
Biopsy

Question 19

List some risk factors for AKI:

Answer 19

• Increasing age
• Diabetes mellitus
• Cancer
• Trauma
• Sepsis
• Dehydration

Question 20

Why is it important to restrict Na+ and water intake in AKI?

Answer 20

To reduce fluid retention and overload, as kidneys cannot adequately excrete fluid/toxins

Question 21

Give some treatments for high [K+] in AKI:

Answer 21

• Restrict dietary K+
• Calcium gluconate
• IV Insulin + Dextrose
• Stop K+ sparing diuretics +/- ACEi / ARBs

Question 22

What is the treatment of acidosis caused by AKI?

Answer 22

Sodium bicarbonate

Question 23

In which situations may you perform dialysis on a patient with AKI?

Answer 23

• Presence of dialysable nephrotoxin
• Hyperkalaemia not responding to treatment
• Severe metabolic acidosis
• Fluid overload not responding to diuretics
• Signs of uraemia (^thirst, muscle cramps, confusion, anorexia, fatigue, nausea/vomiting, pruritis)

Question 24

If hyperkalaemia or fluid overload in AKI is not responding to treatment, what could be considered?

Answer 24

Dialysis

Question 25

If patient with AKI has the following symptoms:
Increased thirst, pruritus, confusion, anorexia, fatigue, muscle cramps…
What do you suspect and how will you treat it?

Answer 25

Uraemia

Dialysis