Acute Kidney Injury

Question 1

Definition

Answer 1

Abrupt decrease in kidney function- rise in serum creatinine by 26.4 micro mols or 50%
Fall in urine output <0.5ml/kg/hour >6 hours

Question 2

Most common cause of AKI

Answer 2

Acute tubular necrosis

Question 3

Pre- renal causes

Answer 3

Hypovolaemia- burns, D+V, Haemorrhage
Hypotension- cardiogenic shock, sepsis, anaphylaxis
Hypoperfusion- NSAIDS, COX inhibitors, hepatorenal syndrome

Question 4

Renal causes

Answer 4

Vascular- thrombosis, embolism, vasculitis, polyarteritis nodosa
Glomerular- acute GN, acute vasculitis, SLE, HSP, good pastures
Interstitial nephritis - drug induced (NSAID, Cephalosporins), TB, Sarcoidosis, lymphoma
Tubular injury- contrast, rhabdomyolysis, hypercalcaemia

Question 5

Post renal causes

Answer 5

Stones
Cancer
Strictures
External compression

Question 6

Pathophysiology of pre-renal AKI

Answer 6

Volume depletion leads to decreased effective intravascular volume
Increased ADH + aldosterone leads to salt and water retention –> oliguria + AKI

Question 7

Pathophysiology of renal AKI

Answer 7

inflammation/damage to cells

Question 8

Pathophysiology of post-renal AKI

Answer 8

Obstruction of urine flow leading to hydronephrosis + loss of contracting ability

Question 9

Symptoms of AKI

Answer 9

Decreased urine output 
Fluid retention - oedema 
Anorexia, weight loss, fatigue
vomiting 
SOB, palpitations

Question 10

Signs of AKI

Answer 10

Hypertension
Pulmonary oedema 
Plural effusions
Uraemia- itch, pericarditis 
Oliguria

Question 11

Investigations

Answer 11

U+Es
FBC + Coagulation screen
Urinalysis 
USS KUB
Immunology 
Biopsy

Question 12

When is a biopsy indicated

Answer 12

suspected rapidly progressing GN

+ve immunology + AKI

Question 13

Stage 1 classification of AKI

Answer 13

Creatinine >26.4 or increase by 150-200%

Question 14

Stage 2 classification of AKI

Answer 14

Creatinine increase by 200-300%

Question 15

Stage 3 classification of AKI

Answer 15

Creatinine increase by 300% or >350micromols or need for renal replacement therapy

Question 16

When is haemodialysis indicated

Answer 16

Hyperkalaemia
Severe acidosis 
Fluidoverload 
Pericardial effusion
Urea >40

Question 17

Appearance of acute tubular necrosis in the urine

Answer 17

Muddy brown casts

Question 18

what is the urine sodium like in a pre-renal AKI

Answer 18

Low urine sodium

- kidney is trying to concentrate urine and retain sodium

Question 19

what is the urine sodium like in a renal AKI e.g. acute tubular necrosis

Answer 19

High urine sodium

- kidney can no longer concentrate urine and retain sodium

Question 20

what drugs can cause acute interstitial nephritis

Answer 20

penicillin
NSAIDS
rifampicin

Question 21

what is seen with acute interstitial nephritis

Answer 21

eosinophilia

Question 22

AKI causes what blood gas result

Answer 22

metabolic acidosis

Question 23

what antibiotic can cause acute tubular necrosis

Answer 23

gentamicin