(SYNOPTIC) Renal - AKI Flashcards
Define Acute Kidney Injury (AKI)
An abrupt/acute (developing over hours/days) decline in kidney function (e.g. glomerular filtration) based on how much the serum creatinine has increased from its normal (baseline) level over a set period of time, or how much the urine volume has decreased over a set period of time
What are the 2 factors AKI is based on?
- Serum Creatinine
- Urine Output
What are the 3 stages of AKI and explain each one
- Stage 1 - Serum creatinine levels = 1.5-1.9 times baseline OR ≥0.3mg/dl (≥26.5mmol/L) increase, Urine Output = <0.5ml/kg/h for 6-12 hours
- Stage 2 - Serum creatinine levels = 2.0-2.9 times baseline, Urine Output = <0.5ml/kg/h for ≥12 hours
- Stage 3 - Serum creatinine levels = 3.0 times baseline OR Increase in serum creatinine to ≥4.0mg/dl (≥353.6mmol/L) OR Initiation of renal replacement therapy OR In patients <18 years, decrease in eGFR to <35ml/min per 1.73²m, Urine Output = <0.3ml/kg/h for ≥24 hours OR Anuria for ≥12 hours
What are the classifications of AKI?
- Pre-renal
- Post-renal
- Intrinsic
What do the 3 classifications of AKI depend on?
where in the kidney the injury has taken place
What are the 3 classifications of AKI, mechanisms and causes of each one
- Pre-renal = Blood flow to the kidney is reduced e.g. decreased perfusion (if not managed, it can cause ischaemic injury)Causes: Reduced blood pressure, hypovolaemia, dehydration, gastro-intestinal (GI) bleed, sepsis, cardiac and liver failure, burns, medications
- Post-renal = Obstruction to outflow from the kidneys (kidney itself functions fine, but urine can’t flow out of kidney due to blockage of ureter e.g. tumour is blocking)Causes: Benign prostatic hypertrophy (BPH), prostate cancer, renal calculi, retroperitoneal fibrosis, medications
- Intrinsic = Damage to the functional tissues of the kidneyCauses: Acute interstitial nephritis (hypersensitivity reactions which are often drug induced), myeloma, rhabdomyolysis, immunological renal disease (e.g. vasculitis), medications
What is pre-renal AKI?
Reduced blood flow to the kidney
What causes pre-renal AKI?
- Reduced BP
- Hypovalaemia (decreased blood volume)
- Dehydration
- GI bleed
- Sepsis
- Cardiac & liver failure
- Burns
- Medications
What is post-renal AKI?
Obstruction to outflow from the kidneys
What causes post-renal AKI?
- Benign prostatic hypertrophy (BPH)
- Prostate cancer
- Renal calculi
- Retroperitoneal fibrosis
- Medications
What is intrinsic AKI?
Damage to the functional tissues of the kidney
What causes intrinsic AKI?
- Acute interstitial nephritis
- Myeloma
- Rhabdomyolysis
- Immunological renal disease
- e.g. vasculitis/ medications
What is the most and least common classification of AKI?
Most common = Pre-renal (75-80%)
Least common (rarest) = Post-renal (5-10%)
What are the risk factors for AKI?
- ≥65 years old
- dehydration
- CKD (AKI on CKD)
- history of urological obstructions
- chronic conditions such as heart failure, liver disease, diabetes
- sepsis/sever infections
- medications (NSAIDs, ACE inhibitors, Diuretics, Aminoglycoside e.g. Gentamycin)
- dyes (Iodine-based contrast agents)
Why is it important to check blood creatinine levels in renal patients?
- Kidneys maintain blood creatinine at specific levels
- If creatinine levels in the blood are rising, it could indicate that the kidneys are not functioning to their full ability to clear the creatinine
- Therefore blood creatinine levels are a good indicator of kidney injury (Higher creatinine = Worse kidney function)
