acute kidney injury W3

Question 1

name for structural support in glomerulus?

Answer 1

mesangium

Question 2

definition of acute kidney injury?

Answer 2

increase in serum creatinine by >26.5μmols/L in 48 hours or,

increase in serum creatinine by >1.5x baseline creatinine within last 7 days or,

urine volume <0.5ml/kg/hr for 6 hours

Question 3

staging system for AKI: AKIN 1?

Answer 3

(SCr = serum creatinine)

increase in SCr > 26.5 μmol/L in 48 hrs or

SCr > 1.5-1.9 fold over baseline SCr

Question 4

staging system for AKI: AKIN 2?

Answer 4

increase in SCr > 2-2.9 fold over baseline SCr

Question 5

staging system for AKI: AKIN 3?

Answer 5

increase in SCr > 3 fold over baseline SCr or

increase in SCr >394 μmol/L or

started on dialysis

Question 6

adverse renal outcomes that severe AKI is independently associated with?

Answer 6

increase incidence of chronic kidney disease
increased incidence of end-stage renal disease

Question 7

what is AKI

Answer 7

a syndrome (not a formal diagnosis)
so need to think about the underlying cause

Question 8

differential diagnosis of AKI?

Answer 8

pre-renal (reduced real/effective blood volume)

renal (glomerulus, tubules, interstitium)

post-renal (obstruction - multiple levels, eg ureter, bladder etc)

Question 9

pre-renal causes of AKI?

Answer 9

hypovolaemia eg bleeding, 3rd space fluid losses, excessive diuretic therapy

hypotension eg sepsis, cardiogenic shock, liver failure

reduced renal blood supply secondary to severe renovascular disease (+/- ACEi), dissection of abdominal aorta etc

Question 10

post-renal causes of AKI?

Answer 10

note - need obstruction of all kidneys to result in AKI

causes:
prostate - hypertrophy, cancer
bladder lesions - tumour
ureter - calculi, tumour, extrinsic compression (retroperitoneal fibrosis, tumour)

Question 11

what is myeloma in the kidney?

Answer 11

intrarenal obstruction. B cell neoplasm, makes many of one antibody, precipitates in kidney and all tubules blocked up.

Question 12

how is obstruction diagnosed? when must this be done?

Answer 12

imaging (often ultrasound - cheap and portable)
must be done within 24 hours in all patients with significant acute kidney injury to exclude/demonstrate obstruction.

Question 13

renal causes of AKI?

Answer 13

acute tubular injury (ATI) - most common

Tubulointerstitium
Glomerular disease
Blood vessels

Question 14

causes of ATI?

Answer 14

tubular toxins (gentamicin, cisplatinum (chemo), NSAIDs)
severe prolonged hypotension (sepsis, MI)
renal hypoperfusion (eg elderly patient on ACEi/diuretic who has D&V)
initial oliguria then may exhibit polyuric recovery phase

Question 15

what causes 50% of all acute renal failure?

Answer 15

renal ischaemia

Question 16

where does renal ischaemia mainly affect the kidney? what does this cause?

Answer 16

outer medulla. causes cells to fall apart!

Question 17

treatment?

Answer 17

none

Question 18

tubulointerstitial causes?

Answer 18

acute allergic interstitial nephritis:

drug related eg PPIs (omeprazole), antibiotics, diuretics, NSAIDs
may have an eosinophilia (no rash)
often respond well to steroids

Question 19

glomerular causes of AKI?

Answer 19

rapidly progressive glomerulonephritis (RPGN): immune aetiology and characterised by ‘glomerular crescents’

Question 20

examples of cresentic RPGN?

Answer 20

Goodpasture’s syndrome
Wegener’s granulomatosis
Microscopic polyarteritis
SLE: anti-nuclear Ab

Question 21

goodpasture’s syndrome features?

Answer 21

antibody binds to basement membrane.

Question 22

microscopic polyarteritis staining pattern?

Answer 22

‘perinuclear’ pattern

Question 23

Wegeners granulomatosis staining pattern?

Answer 23

‘cytoplasmic’ pattern

Question 24

vascular causes of AKI?

Answer 24

haemolytic uraemic syndrome (HUS)
E coli related
familial cases

Question 25

haemolytic uraemic syndrome - affect on glomeruli?

Answer 25

glomerular microvascular thrombosis

Question 26

features of AKI history?

Answer 26

renal history (pre-existing renal disease, diabetes, family history)
urine volume
drug history (new drugs, nephrotoxic drugs)
systemic symptoms - diarrhoea, rashes etc

Question 27

features of clinical examination in AKI?

Answer 27

fluid status - dehydrated? (JVP, postural BP)
evidence of infection?
rash, joint pathology
arterial bruits? (underlying renovascular disease)
palpable bladder (obstruction)
check drug chart!

Question 28

investigations in AKI?

Answer 28

urine dipstick (important! - blood, protein)
urine culture
renal ultrasound
renal biopsy
angiography

Question 29

blood tests for AKI?

Answer 29

FBC, blood film, clotting screen
biochemistry (Ca2+, PO4^2-, LFTs and albumin)
creatinine kinase (rhabdomyolysis)
blood cultures
virology and serology (eg hep B, ASOT)

Question 30

features of urine with rhabdomyolysis

Answer 30

dark colour - cocacola!

Question 31

immunological tests?

Answer 31

IgGs and serum electrophoresis (myeloma)
complement levels (SLE, post strep GN)
autoantibodies

Question 32

general treatment of AKI?

Answer 32

optimise fluid balance and circulation
stop exacerbating factors eg nephrotoxic drugs
appropriate prescribing
supportive treatment eg dialysis, nutrition

Question 33

specific treatment of AKI?

Answer 33

obstruction - drain renal tract
sepsis - antibiotics
RPGN (eg SLE) - immunosuppression
Goodpasture’s syndrome - plasma exchange
compartment syndrome - fasciotomy

Question 34

institution of dialysis?

Answer 34

severe uraemia:
-no prospect of immediate improvement
-uraemic encephalopathy or seizures
-uraemic pericarditis

hyperkalaemia unresponsive to medical treatment (>6.5)

fluid overload (especially PO), resistant to diuretics/fluid restriction

severe acidosis (results in myocardial depression and hypotension)

Question 35

how is dialysis carried out?

Answer 35

intermittent haemodialysis
continuous haemodialysis