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Flashcards in Acute Kidney Injury Deck (16):

Acute kidney injury

A rapid loss (<48hrs) of kidney function (eGFR) due to reduced blood flow, harmful substances or urinary track obstruction. It is diagnosed on increased blood urea, creatinine and failure to produce urine (oligouria over 6hr or more)


Causes of AKI

Pre-renal --> Reduced perfusion, rhabomyolysis
Renal --> Glomerular, Atheroembolic, tubular necrosis
Obstructive/Post-renal --> BPH & stones


Reduced Perfusion leading to AKI

Can be hypovolaemic (bleeding or cutaneous loss) or hypotensive (HF, shock, Drugs, dehydration)
Renal ischemia due to stenosis or embolism
Urea is much higher than creatinine & urinary Na is low --> Responds to fluid therapy


Rhabomyolysis leading to AKI

Major Muscle necrosis (trauma, extertion, immobility) or drugs (statins or neuroleptics)
Causes heme-pigment toxicity with raised CK, brown urine without RBCs
Treat with fluid and bicarbonate (myoglobin is more soluble in alkali)


Glomerular Causes of AKI

Any kind of active urinary sediment (myoglobin or immune complexes) will cause damage and the presence of blood, protein and red cell casts in the urine


Atheroembolic Disease leading to AKI

May cause a pre-renal AKI due to stenosis/embolism
May also occur post-angiography with allergy like symptoms.
Presents with sterile pyuria and eosinophila


Acute tubular Necrosis

Follows any form of hypoperfusion
Can be atheroembolic or toxic (rhabomyolytic or drugs) --> particularly gentamicin, contrast, antivirals, antifungals


Sign of Acute Tubular necrosis

'Muddy brown epithelial cell casts' are pathognomic


Treatment of Renal AKI

Does not respond to fluids
Will take weeks to recover to baseline
High urinary sodium


Obstructive causes of AKI

Must occur in both kidneys for AKI to occur
Most commonly Stones or BPH
Will lead to retention and painful anuria (<50ml/day)


Management of obstructive AKI

USS urgently and catheterise to relieve obstruction
Watch for large volumes of diuresis
Monitor output and replace electrolytes


Indications for Haemodialysis after AKI

Ureamia (>30mmol/L)
Refractory fluid overload
Metabolic acidosis
Severe hyperkalaemia


Hyperkalaemia post AKI

Palpitations and ECG changes
May need Dialysis


Metabolic acidosis

pH 7.1 or below
Increased Resp rate
Monitor and replace electrolytes
May need Dialysis


Refractory fluid overload

Can be a consequence of AKI or treatment for AKI
Will present with crackles, orthopnoea and hypoxia
Treat with diuretics



Can cause encephalopathy or pericarditis
Can present as confusion, or pleuritic central chest pain with a pericardial rub
Requires Dialysis