Acute Kidney Injury Flashcards
What are some examples of nephrotoxic drugs?
NSAIDs
aminoglycosides
ACE inhibitors/angiotensin II receptor antagonists
diuretics
The criteria for diagnosing AKI looks at what parameter(s)?
Rise in creatinine OR
Fall in urine output OR
Fall in eGFR in children / young adults
In terms of creatinine, what is the criteria for diagnosing AKI?
Rise in creatinine of 26µmol/L or more in 48 hours OR
>= 50% rise in creatinine over 7 days
In terms of fall in urine output, what is the criteria for diagnosing AKI?
Fall in urine output to less than 0.5ml/kg/hour for more than 6 hours in adults (8 hours in children)
In terms of egfr, what is the criteria for diagnosing AKI?
> = 25% fall in eGFR in children / young adults in 7 days
what increases the risk of AKI?
Surgery: Emergency surgery, ie, risk of sepsis or hypovolaemia, Intraperitoneal surgery
CKD, ie if eGFR < 60
Age >65 years
Disease: Liver disease, Diabetes, Heart failure
Acute kidney injury (AKI), previously termed acute renal failure, describes what?
reduction in renal function following an insult to the kidneys
Around what % of patients admitted to hospital develop AKI?
15%
NICE estimate that inpatient mortality of AKI in the UK might typically be 25-30% or more
true
Causes of AKI are traditionally divided into?
prerenal, intrinsic and postrenal causes
What are some examples of prerenal AKI causes?
hypovolaemia secondary to diarrhoea/vomiting
renal artery stenosis
What can cause intrinsic AKI?
toxins (drugs, contrast etc) or immune-mediated glomuleronephritis.
What are some examples of conditions that can result in intrinsic AKI?
glomerulonephritis acute tubular necrosis (ATN) acute interstitial nephritis (AIN), respectively rhabdomyolysis tumour lysis syndrome
What are some example causes of postrenal AKI?
kidney stone in ureter or bladder
benign prostatic hyperplasia
external compression of the ureter
use of iodinated contrast agents within the past what is a risk factor for AKI?
week
Define oliguria
urine output less than 0.5 ml/kg/hour
What steps can be undertaken for patients who are at risk of AKI and who are undergoing an investigation requiring contrast?
IV fluids
Certain drugs such as ACE inhibitors and ARBs may also be temporarily stopped.
How would AKI present?
Many patients with early AKI may experience no symptoms. However, as renal failure progresses the following may be seen:
reduced urine output
pulmonary and peripheral oedema
arrhythmias (secondary to changes in potassium and acid-base balance)
features of uraemia
What are the features of uraemia?
pericarditis or encephalopathy
What is a common blood test that can help detect AKI? What does this include?
'urea and electrolytes' or 'U&Es'. This returns a number of markers, including sodium potassium urea creatinine
all patients with suspected AKI should have what investigation?
urinalysis
if patients have no identifiable cause for the deterioration or are at risk of urinary tract obstruction they should have what investigation?
renal ultrasound within 24 hours of assessment.
What are the principles of AKI management?
Largely supportive
Fluid balance - to ensure that the kidneys are properly perfused but not excessively to avoid fluid overload
Review medications
What medications should be stopped in AKI as may worsen renal function?
- NSAIDs (except if aspirin at cardiac dose e.g. 75mg od)
- Aminoglycosides
- ACE inhibitors
- Angiotensin II receptor antagonists
- Diuretics
What medications may have to be stopped in AKI?
• Metformin
• Lithium
• Digoxin
May have to be stopped in AKI as increased risk of toxicity (but doesn’t usually worsen AKI itself)
What medications are usually SAFE to continue in AKI?
- Paracetamol
- Warfarin
- Statins
- Aspirin (at a cardioprotective dose of 75mg od)
- Clopidogrel
- Beta-blockers
loop diuretics are routinely reccomended to artificially boost urine output
FALSE
not recommend
There is however a role for loop diuretics in patients who experience significant fluid overload.
low-dose dopamine are routinely reccomended (in an attempt to increase renal perfusion)
false
Hyperkalaemia needs prompt treatment to avoid arrhythmias which may potentially be life-threatening.
true
What is the role of Intravenous calcium gluconate in management of hyperkalaemia?
Stabilisation of the cardiac membrane
What medications aid Short-term shift in potassium from extracellular to intracellular fluid compartment in hyperkalaemia?
- Combined insulin/dextrose infusion
* Nebulised salbutamol
What medications remove potassium from the body in hyperkalaemia?
- Calcium resonium (orally or enema)
- Loop diuretics
- Dialysis
When is Renal replacement therapy (e.g. haemodialysis) used in the context of AKI?
when a patient is not responding to medical treatment of complications
What are the complications of AKI?
hyperkalaemia
pulmonary oedema
acidosis
uraemia
DAMN mnemonic for drugs to stop in AKI -
diuretics, ACEi/ ARBs, metformin, NSAIDs
Why would Metformin be held in the context of AKI?
can cause Lactic Acidosis so must be stopped, if egfr is 30 or less then patients cannot take metformin
What investigation would you do if you suspected hydronephrosis?
US KUB
Renal artery stenosis is caused by?
atherosclerosis accounts for around 90%
fibromuscular dysplasia being the most common cause of the remaining 10%.
What are the features of renal artery stenosis?
hypertension
kidney disease (chronic or AKI)
‘flash pulmonary oedema’
Acute interstitial nephritis accounts for what % of drug-induced acute kidney injury?
25%
What can cause Acute interstitial nephritis?
drugs: the most common cause, particularly antibiotics
systemic disease: SLE, sarcoidosis, and Sjögren’s syndrome
infection: Hanta virus , staphylococci
What specific drugs can cause Acute interstitial nephritis?
penicillin rifampicin NSAIDs allopurinol furosemide
Describe the histology of Acute interstitial nephritis?
marked interstitial oedema and interstitial infiltrate in the connective tissue between renal tubules
Describe the symptoms & features of Acute interstitial nephritis?
fever, rash, arthralgia
eosinophilia
mild renal impairment
hypertension
What will you see in urinalysis of Acute interstitial nephritis?
sterile pyuria
white cell casts
Eosinophilic casts
Tubulointerstitial nephritis with uveitis (TINU) usually occurs in which group?
young females.
What are the symptoms of Tubulointerstitial nephritis with uveitis (TINU) ? What would urinalysis show?
fever, weight loss and painful, red eyes
Urinalysis is positive for leukocytes and protein.
What is the most common cause of AKI?
Acute tubular necrosis (ATN)
Is Acute tubular necrosis (ATN) reversible?
In the early stages ATN is reversible if the cause if removed.
What are the two main causes of Acute tubular necrosis (ATN) ?
ischaemia: shock, sepsis
nephrotoxins: aminoglycosides, myoglobin secondary to rhabdomyolysis, radiocontrast agents, lead
What are the features of Acute tubular necrosis (ATN) ?
features of AKI: raised urea, creatinine, potassium
muddy brown casts in the urine
What are the histo-pathological featyres of Acute tubular necrosis (ATN) ?
tubular epithelium necrosis: loss of nuclei and detachment of tubular cells from the basement membrane
dilatation of the tubules may occur
necrotic cells obstruct the tubule lumen
What are the 3 phases of ATN?
oliguric phase
polyuric phase
recovery phase
What is tumour lysis syndrome?
breakdown of the tumour cells and the subsequent release of chemicals from the cell.
Associated with treatment of high-grade lymphomas and leukaemias.
It can occur in the absence of chemotherapy but is usually triggered by the introduction of combination chemotherapy.
tumour lysis syndrome can sometimes arise from steroid treatment alone
true
When should you suspect tumour lysis syndrome in AKI?
presence of a high phosphate and high uric acid level
What electrolyte imbalances can tumour lysis result in?
high potassium and high phosphate level in the presence of a low calcium.
Patients at high risk of TLS should be given what medications immediately prior to and during the first days of chemotherapy?
IV allopurinol or IV rasburicase
Patients in lower-risk groups should be given oral allopurinol during chemotherapy cycles in an attempt to avoid the condition.
Why should Rasbicurase and allopurinol not be given together?
reduces the effect of rasburicase
How does rasburicase work?
Rasburicase is a recombinant version of urate oxidase, an enzyme that metabolizes uric acid to allantoin. Allantoin is much more water-soluble than uric acid and is, therefore, more easily excreted by the kidneys.
How is TLS graded?
Cairo-Bishop scoring system
Describe the Cairo-Bishop scoring system
Laboratory tumor lysis syndrome: abnormality in two or more of the following, occurring within three days before or seven days after chemotherapy. uric acid > 475umol/l or 25% increase potassium > 6 mmol/l or 25% increase phosphate > 1.125mmol/l or 25% increase calcium < 1.75mmol/l or 25% decrease
What is clinical TLS?
laboratory tumour lysis syndrome plus one or more of the following:
increased serum creatinine (1.5 times upper limit of normal)
cardiac arrhythmia or sudden death
seizure
