Acute Kidney Injury

Question 1

What is acute kidney injury?

Answer 1

a rapid (hours to days) decline in kidney function

Question 2

What are the stages of AKI?

Answer 2

Stage 1, stage 2, stage 3

Question 3

Who is at risk of AKI?

Answer 3

older age
diabetes mellitus
hypertension
heart disease
liver disease
chronic kidney disease
medication

Question 4

What medications can cause AKI?

Answer 4

diuretics
ACEi/ARB
NSAID
gentamicin
vancomycin
chemotherapy

Question 5

What can the cause of AKI be classified into?

Answer 5

Pre-renal = perfusion failure
Renal = intrinsic disease of the kidney
Post-renal = obstruction of the urinary system

Question 6

Give some pre-renal causes of AKI?

What are these made worse by?

Answer 6

hypotension
hypovolaemia
renal artery occlusion 
made worse by:
- RAAS blockade
- NSAIDs
- antihypertensives
- diuretics

Question 7

What is the renal autoregulatory range?

Why is this important?

Answer 7

90-200mmHg
If there is drop in blood pressure or blood volume renal perfusion and urine production will be maintained. But if drop is outside of autoregulatory range then perfusion and urine prodcuction cannot be maintained

Question 8

What are the steps of RAAS that can be inhibited with drugs?

Answer 8

Inhibit renin = stop conversion of angiotensinogen to angiotensin I
ACE inhibitors = Angiotensin I to angiotensin II
Block efferent arteriolar constriction
block mineralcorticoid receptor antagonist

Question 9

How can drugs lead to pefusion failure?

Answer 9

RAS blockade

no compensatory changes in afferent/efferent so autoregulatory ranges change and you lose perfusion

Question 10

What are the histological signs of perfusion failure?

Answer 10

acute tubular necrosis

Question 11

What is the treatment of perfusion failure?

Answer 11

treat the underlying cause 
- fluid volume replacement 
- blood pressure support (inotropes)
restore arterial patency 
- stop RAS blockade
- stop NSAID

Question 12

What things can cause post renal obstruction?

Answer 12

stones
benign prostate
tumours (extrinsic/instrinsic)
fibrosis

Question 13

What is the treatment of excretion?

Answer 13

bypass to remove obstruction

• nephrostomy
• bladder catheter
• lithotripsy
• tumour removal
• dilating strictures

Question 14

What are the ‘renal’ causes of renal failure?

Answer 14

Diseases the damage the 
- tubules
- glomerulus
- interstitium
Systemic diseases
- vasculitis, SLE, myeloma
Infection 
- HIV, endocarditis
Allergic (to antibodies)
- acute interstitial nephritis 
Drug toxicity 
- gentamycin, NSAID, chemotherapy 
Glomerulonephritis

Question 15

What is ANCA associated vasculitis?

Answer 15

Anti-neutrophil cytoplasm antibodies

• airway and renal organs most commonly involved
• cause life threatening acute or chronic organ damage

Question 16

What do ANCA do?

Answer 16

they activate neutrophils

Question 17

What are the histological signs of renal vasculitis?

Answer 17

necrotic cells
inflammatory cells
compressed glomerular tuft

Question 18

How inflammatory renal disease? What are the risks/complications of these treatments?

Answer 18

Steroids
- diabetes, infection, osteoporosis, skin damage, weight gain
Cyclophosphamide
- infections, malignancy, bone marrow suppression, infertility,
Plasma exchange
- infection, bleeding, risks of central lines
Azathioprine/Mycophenolate
- infection, cancer, liver abnormalities

Question 19

What are the causes of death in AKI?

Answer 19

underlying disease
infection
hyperkalaemia
acidosis
pulmonary oedema