AKI

Question 1

Define AKI

Answer 1

an abrupt loss of kidney function resulting in the retention of urea and other nitrogenous waste products and the dysregulation of extracellular volume and electrolytes.

NOTE: this can occur in patients with previously normal kidneys or in patients with pre-existing renal disease

Question 2

KDIGO Classification of AKI

Answer 2

Increase in serum creatinine > 26 mmol/L within 48 hrs

Increase in serum creatinine to > 1.5 times baseline within the preceding 7 days

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

Question 3

Aetiology: Pre-Renal (90%)

Answer 3

Hypovolaemia (e.g. haemorrhage, severe vomiting)

Heart failure

Cirrhosis

Nephrotic syndrome

Hypotension (e.g. shock, sepsis, anaphylaxis)

Renal hypoperfusion (e.g. NSAIDs, ACE inhibitors, ARBs, renal artery stenosis)

Question 4

Aetiology: Intrinsic Renal

Answer 4

Glomerular - glomerulonephritis, haemolytic uraemic syndrome

Tubular - acute tubular necrosis

Interstitial - acute interstitial nephritis (e.g. NSAIDs, autoimmune)

Vasculitides (e.g. Wegener’s granulomatosis)

Eclampsia

Question 5

Aetiology: Post-Renal

Answer 5

(due to obstruction)

Calculi- stone

Urethral stricture- scarring

Prostatic hypertrophy or malignancy

Bladder tumour

Question 6

RISK FACTORS

Answer 6

Age

Chronic kidney disease

Comorbidities (e.g. heart failure)

Sepsis

Hypovolaemia

Use of nephrotoxic medications

Emergency surgery

Diabetes mellitus

Question 7

Summarise the epidemiology of AKI

Answer 7

15% of adults admitted to hospital will develop an AKI

Most common in the ELDERLY

Question 8

Recognise the presenting symptoms of AKI

Answer 8

Depends on underlying CAUSE

Oliguria/anuria

NOTE: abrupt anuria suggests post-renal obstruction

Nausea/vomiting

Dehydration

Confusion

Question 9

Recognise the signs of AKI on physical examination

Answer 9

Hypertension

Distended bladder

Dehydration - postural hypotension

Fluid overload (in heart failure, cirrhosis, nephrotic syndrome) - raised JVP, pulmonary and peripheral oedema

Pallor, rash, bruising (vascular disease)

Question 10

Identify appropriate investigations for AKI

Answer 10

urinanalysis
bloods
ultrasound
other imaging

Question 11

Urinanalysis

Answer 11

Blood - suggests nephritic cause

Leucocyte esterase and nitrites - UTI

Glucose

Protein

Urine osmolality

Question 12

Bloods

Answer 12

FBC

Blood film

• U&Es
• Clotting
• CRP

Immunology

• Serum immunoglobulins and protein -electrophoresis - for multiple myeloma
• Also check for Bence-Jones proteins in the urine
• ANA - associated with SLE
• Also check anti-dsDNA antibodies (high in active lupus)
• Complement levels - low in active lupus
• Anti-GBM antibodies - Goodpasture’s syndrome
• Antistreptolysin-O antibodies - high after Streptococcal infection

Virology - check for hepatitis and HIV

Question 13

Ultrasound

Answer 13

Check for post-renal cause

Look for hydronephrosis

Question 14

Other Imaging

Answer 14

CXR - pulmonary oedema

AXR - renal stones

Question 15

Generate a management plan for AKI

Answer 15

Protect patient from hyperkalaemia (calcium gluconate)

Optimise fluid balance

Stop nephrotoxic drugs

Consider for dialysis

Question 16

Renal Replacement Therapy (RRT) considered if:

Answer 16

Hyperkalaemia refractory to medical management

Pulmonary oedema refractory to medical management

Severe metabolic acidaemia

Uraemic complications

Question 17

Identify possible complications of AKI

Answer 17

Pulmonary oedema

Acidaemia

Uraemia

Hyperkalaemia

Bleeding

Question 18

Summarise the prognosis for patients with AKI

Answer 18

Inpatient mortality varies depending on cause and comorbidities

Indicators of poor prognosis:

Age

Multiple organ failure

Oliguria

Hypotension

CKD

Patients who develop AKI are at increased risk of developing CKD