Acute Kidney Injury Flashcards
What is the definition of AKI from the UKRA guidelines?
Decline of renal excretory function over hours or days, recognised by the rise in serum urea and creatinine
How can you classify the severity of AKI?
AKI-KDIGO
•Stage 1
•Stage 2
•Stage 3
What is stage 1 AKI?
Serum creatinine >/1.5 and <2 times the AKI baseline or >/26.0micro mol/l increase above the AKI baseline
What is stage 2 AKI?
Serum creatinine >/2 and <3 times the AKI baseline
What is stage 3 AKI?
Serum creatinine >/3 times the AKI baseline or >/354 micro mol/l increase above the AKI baseline
Define oliguria
Urine output that is less than 1mL/kg/h in infants, less than 0.5mL/kg/hour in children and less than 400mL or 500mL per 24 hours in adults
Explain what AKI e-alerts are
- They highlight AKI using lab data algorithm
- Serum creatinine >/1.5 times higher than the median of all creatinine values 8-365 days ago
- Serum creatinine >/1.5 times higher than the lowest creatinine within 7 days
- Serum creatinine >26micromol/l higher than the lowest creatinine within 48 hours
What are the diagnostic classifications of AKI?
- Pre renal = circulatory failure
- Renal
- Post renal = obstruction
What are the pre renal causes of acute kidney injury?
•Hypovolaemia and hypotension due to:
- diarrhoea/vomiting
- inadequate fluid intake
- blood loss through trauma
- third space fluid losses
•Reduced effective circulating volume
- circulating volume
- cardiac failure
- septic shock (vasodilation so effective perfusion decreases)
- cirrhosis
•Drugs (in setting of hypovolaemia)
- NSAIDs
- ACEi
•Renal artery stenosis
What are the renal causes of AKI?
- Glomerular - glomerulonephritis
- Tubular (obstruction and dysfunction)
- ischaemic ATN
- nephrotoxic ATN
- myeloma cast nephropathy
•Tubulointerstitial
- drugs
- myeloma
- sarcoid
What are the post renal causes of AKI?
Anything between the renal pelvis and urethral meatus which obstructs the flow of urine •Renal papillary necrosis •Kidney stones •Retroperitoneal fibrosis •Carcinoma of the cervix •Prostatic hypertrophy/malignancy •Tumours: ureter, bladder, prostate, cervix, ovarian, cna be extrinsic •lymph nodes •Urethral strictures
What two key things are needed for the kidneys to make urine?
- A blood supply
* An un-obstructed collecting system to ensure urine can be excreted
What will you see on ultrasound of an obstructed kidney?
Dilated renal pelvis surrounded by renal cortical tissue
If a man presents with an obstructive cause of AKI, what is the first thing to rule out?
Prostate
If a woman presents with obstructive causes of AKI, what is the first thing to rule out?
Gynaecological tumour
What are the categories of acute tubular necrosis?
- ischaemic
* Toxic
What is the most common intrinsic AKI cause?
Acute tubular necrosis
What drug can affect the glomeruli causing an AKI?
Gentamicin
What are the tubular renal causes of AKI?
- Tubulo-interstitial nephritis
* Rhabdomyolysis
What is the cause of acute tubular necrosis?
- Any pre-renal cause of AKI if severe/of sufficient duration
- Under perfusion of the tubules and/or direct toxicity
- Hypotension
- Sepsis
- Toxins
- Can be all 3 of above
What is the prognosis of acute tubular necrosis?
- It is usually reversible
- 10-15% won’t recover renal function
- A further 10-15% will have chronic renal impairment following ATN putting them at risk of progressive kidney disease
Describe the histology of acute tubular necrosis
- Focal loss of tubular epithelial cells
- Partial occlusion of tubular lumens by cellular debris
- In recovery phase: multiple mitoses indicative of regenerating tubular cells
What are the exogenous toxins causing ATN?
- Drugs (e.g. NSAIDs, gentamicin, ACEi)
- Contrast
- Poisons (e.g. metals, anti-freeze)
What are the endogenous toxins causing AKI?
- Myoglobin e.g. rhabdomyolysis
- Haemoglobin
- Immunoglobins
- Calcium
- urate
