Acute Kidney Injury

Question 1

What is an AKI?

Answer 1

A rapid deterioration in kidney failure over hours to days

Question 2

What criteria can be used to stage AKI?

Answer 2

Serum creatinine and urine output

Question 3

What creatinine change is seen in stage 1 AKI?

Answer 3

> 26 increase or 50-100% increase from baseline

Question 4

What urine output change is seen in stage 1 AKI?

Answer 4

<0.5ml/kg/hr for 6 hours

Question 5

What serum creatinine change is seen in stage 2 AKI?

Answer 5

100-200% increase from baseline

Question 6

What urine output change is seen in stage 2 AKI?

Answer 6

<0.5ml/kg/hr for 12 hours

Question 7

What serum creatinine change is seen in stage 3 AKI?

Answer 7

200% or more increase from baseline
>354 micromol/L or more
Or needs dialysis

Question 8

What urine output change is seen with stage 3 AKI?

Answer 8

<0.3 ml/kg/24 hours
Or Anuria for 12 hours
Or needs dialysis

Question 9

AKI be split?

Answer 9

Pre-renal
Renal
Post- renal

Question 10

What are some pre-renal causes of AKI?

Answer 10

Dehydration
Sepsis
Hypo-perfusion
Profound hypotension
Shock
MI (Cardiogenic shock)
Vascular occlusion

Question 11

What are some renal causes of AKI?

Answer 11

IgA nephropathy
Post-streptococcal glomerulonephritis
Lupus nephritis
ANCA Vasculitis
Nephrotoxic drugs (Gentamycin, NSAIDs, Calcineurin inhibitors, chemotherapy)
Myeloma kidney
Infection- ascending UTI, HIV associated glomerulonephritis, pyelonephritis
Allergic- Acute interstitial nephritis
Acute tubular necrosis

Question 12

What are some post renal causes of AKI?

Answer 12

Tumour- Intrinsic (TCC) or Extrinsic (CRC, Prostate)
BPH
Strictures
Retention
Calculi

Question 13

What is the management for AKI?

Answer 13

Treat the underlying cause- e.g:
Percutaneous nephrostomy (if infected obstructed)
Refer to urology
Fluids
Steroids
Immunosuppression

Question 14

What investigations should be done for a patient with AKI?

Answer 14

Depends upon the suspected cause. Some examples:

Urine dip- Nephritic syndromes will show proteinuria and haematuria, stones will show haematuria, infection shown by raised white cells and proteins
Blood cultures- if suspecting sepsis the sepsis 6 should be done
ECG- MI is a cause
Blood Immunology- Causes of intrinsic AKI- ANCA, ANA, Anti GBM, HIV, HBC, HCV
Myeloma Screen- If suspected: Urinary Bence Jones Proteins, Urinary/Serum Free light chains, Serum protein electrophoresis
Check fluid status- BP, CRT, Mucous membranes, conjunctival pallor, temperature, pulmonary oedema, peripheral oedema, fluid chart, urine output, ascites, JVP

Question 15

What should be checked for on a fluid status?

Answer 15

Blood pressure
JVP
Ascites
Pulmonary oedema
Peripheral oedema
CRT
Mucous membranes
Conjunctival pallor
Sunken eyes
Urine output
Fluid chart

Question 16

What important electrolyte should be checked for a patient with AKI?

Answer 16

Potassium- If urgently needs checking consider VBG rather than normal bloods

Question 17

Why might a fall cause and AKI?

Answer 17

Prolonged time of the floor before being found can lead to rhabdomyolysis. This releases myoglobin which is toxic to the kidneys.

Question 18

What things should you ask about in the history in a patient with AKI? Structure your answer according to the causes of AKI

Answer 18

Pre-renal- infection, heart disease, vascular disease, light headedness, recently started any anti-hypertensives,

Renal- Rashes, fatigue and lethargy, headaches, bleeding, recurrent nose bleeds, arthritis, drug history (consider risk of drug reaction)

Post renal- obstructive symptoms (urgency, poor stream, hesitancy), infections (urgency, polyuria), loin pain, thiazide diuretic use

Question 19

For anyone with an AKI what first investigation should be done?

Answer 19

Do a urine dip

Question 20

Why might a urine dip on a patient with a catheter be potentially misleading?

Answer 20

Catheterisation can cause minor trauma with some bleeding which can cause haematuria to be found on a urine dip

Question 21

If a patient presents with AKI but also has yellow ish skin what would you do?

Answer 21

This patient may have hepato-renal syndrome and LFTs should be done to investigate for this as a cause of AKI

This is due to the diseased liver releasing factors which decrease perfusion to the kidneys- therefore a pre-renal cause of AKI.

Question 22

What are some complications of an AKI? How should they be managed?

Answer 22

This will also vary depending on cause
Pulmonary oedema- Oxygen, diuretics, ABGs, ventilation if required
Hyperkalaemia- Calcium gluconate, insulin+glucose, salbutamol, ion exchange resions e.g. calcium resonium
Fluid overload
Infection due to urinary stasis of obstructed- ABx, percutaneous nephrostomy
Metabolic acidosis

Question 23

If measures to control complications from AKI fail what should be done?

Answer 23

Dialysis