Session 10 Flashcards
What is AKI?
A decline in GFR that occurs over a period of <2 weeks. Usually measured by an increase in serum creatinine
What is oliguria and Anuria?
Oliguria: <500ml of urine per day
Anuria: <100ml urine per day
What is pre renal AKI and what can it progress to if not treated?
Decreased renal perfusion if BP falls below a threshold level for autoregulation. Can be reversible as there is no kidney injury (volume responsive).
Can progress to acute tubular necrosis (ATN).
What are the causes of pre renal AKI?
Reduced BP - Hypovolaemia, systemic vasodilation (anaphylaxis, sepsis) or cardiac failure
Impaired renal autoregulation - preglomerular vasoconstriction (NSAIDs/sepsis) or postglomerular vasodilation (ACEi/ang II antagonists)
What is post renal AKI and what can cause it?
Indicates an obstruction to urine flow after it has left the kidneys - in BOTH ureters, bladder or urethra. Obstructions are either in the lumen (stones/tumour), in the wall, or from pressure from the outside (enlarge prostate, tumour, aneurysm)
What is intrinsic AKI and what can cause it?
Results from direct damage to the kidney:
ATN can be due to ischaemic damage (pre renal) or nephrotoxins or both. Nephrotoxins can be endogenous (myoglobin/bilirubin) or exogenous (ACEi, NSAIDs, endotoxin)
Immune diseases
Intra tubular obstruction
Inflammation of kidney interstitium (infection/toxin)
What is the prevalence of different causes of AKI?
Pre renal + ATN = 85%
Post renal = 10%
ATN counts for 90% of intrinsic AKI
Describe the dipstick (proteinuria and haematuria) and microscopy findings for the different causes of AKI
Pre renal - all normal
Glomerulonephritis - protein, blood and RBC on microscopy
ATN - no protein or blood, mouldy brown cast on microscopy
When is ultrasound preformed for AKI?
If obstruction suspected or cause unclear.
When is a kidney biopsy preformed for AKI?
When pre&post renal ruled out and/or systemic inflammatory signs present
How is pre renal AKI treated?
Restoring renal perfusion by restoring volume (fluids) or treating pump failure (diuretics)
How is post renal AKI treated?
Urological intervention to re establish flow
How is ATN treated?
Supportive - maintaining good kidney perfusion, avoiding nephrotoxins and nutritional support
What is rhabdomyolysis?
When damaged skeletal muscle breaks down rapidly (trauma/drug users). The myoglobin that is released in an endogenous nephrotoxin
What are the risk factors for AKI?
Increasing age, CKD, DM, heart/liver disease, cancer, previous AKI
