Renal for Finals Flashcards
What are the diagnostic criteria for acute kidney injury?
- Sudden (within 1 week) rise in creatinine to 1.5x above baseline, where the baseline has been measured within 1 year
- Oliguria (less than 0.5ml/kg/hr) for 6-12 hours
- Anuria for more than 12 hours
How many stages of AKI are there?
3
What is Stage 1 AKI defined as?
Increase in creatinine more than 26umol/L within 48 hours OR 1.5-1.9x baseline OR urine output less than 0.5ml/kg/hr for more than 6 hours
What is Stage 2 AKI defined as?
Increase in creatinine by 2-2.9x baseline OR urine output less than 0.5ml/kg/hr for more than 12 hours
What is Stage 3 AKI defined as?
Increased in creatinine more than 3x baseline OR increase more than 354umol/L OR commencement of acute renal replacement therapy OR anuria for more than 12 hours OR urine output less than 0.3ml/kg/hr for more than 24 hours
True / False: Diagnosis of AKI is made using eGFR
False - eGFR cannot be assessed in AKI as the calculation requires a steady state of renal function. Creatinine is used as a marker of acute kidney injury instead.
If a patient has anuria for more than 12 hours, what stage of AKI are they in?
Stage 3
If a patient has a rise in creatinine of 2.4x their baseline, what stage of AKI do they have?
Stage 2
If a patient has a urine output of 0.4ml/kg/hr for 7 hours, what stage of AKI are they in?
Stage 1
List some drug causes of AKI
Metformin ACE-Inhibitors Aminoglycosides Diuretics Contrast agents NSAIDs Penicillamine
List some pre-renal causes of AKI
Diarrhoea Vomiting Sepsis Hypotension e.g. in cardiac failure, cardiogenic shock Haemorrhage Dehydration
List some renal causes of AKI
Renal tubular acidosis
Glomerulonephritis
Acute interstitial nephritis
Rhabdomyolysis
List some post-renal causes of AKI
Renal or ureteric stones
BPH
Urethral stricture
Malignancy
How would you manage a patient with AKI?
- DR ABCDE approach
- Insert urinary catheter for accurate urine output measurement
- fluid resuscitation if required
- Stop nephrotoxic drugs
- Look for a cause and treat it
- Monitor electrolyte, acid-base balance, weight
- Supportive management e.g. fluids
What investigations would you do in suspected AKI?
- Fluid assessment of the patient
- Full examination e.g. for colicky pain, haemorrhage, etc.
- Observations: ?Tachycardia, ?hypotension, ?pyrexia
- VBG
- Accurate urine output recording
- Urine dip and send for MC+S
- Urine protein:creatinine ratio…If reduced
- Bloods: FBC, U+E, CRP, CK, myeloma screen, autoantibodies, C3/C4, virology
- Consider imaging of renal tract e.g. USS renal tract
Give 2 ways in which uraemia might present
Pericarditis
Encephalopathy
What part of the kidney do ACE-Inhibitors affect?
The efferent renal arteriole
Give 2 drugs which might be toxic to the renal tubule
Gentamicin
Amphoteracin
Do sulphonamides cause pre-renal, renal, or post-renal damage? How?
Post-renal - They might crystallise in the renal tubules causing obstruction
Give a type of drug (with examples) which might cause post-renal damage to kidneys by scarring of the ureters
Ergot derivatives e.g. Methylsergide (migraine) and cabergoline (Parkinson’s)…These can causes retroperitoneal fibrosis and result in scarring of the ureters
What is the glomerular filtration rate?
Volume of filtrate produced by the blood which is flowing through the glomerulus in a unit time
What are the stages of chronic kidney disease?
Stage 1 = eGFR above 90, with evidence of other renal damage
Stage 2 = eGFR 60-90, with evidence of other renal damage
Stage 3 = eGFR 30-60 ± evidence of other renal damage (Stage 3a = eGFR 45-59, stage 3b = eGFR 30-45)
Stage 4 = eGFR 15-30 ± evidence of other renal damage
Stage 5 = eGFR less than 15
What is the creatinine clearance? Why is it useful?
It is the volume of blood which is cleared of creatinine per unit time, and is a useful estimate of eGFR
How do you calculate creatinine clearance?
[ (40 x age) x weight ] / [ 72 x creatinine ] = Creatinine clearance
Multiply by 0.85 if female
Give 2 congenital causes of chronic kidney disease
Autosomal dominant polycystic kidney disease
Alport’s disease
List some complications of chronic kidney disease
Anaemia Metabolic abnormalities: Hyperkalaemia Hyperphosphataemia Secondary hyperparathyroidism Hypocalcaemia Fluid retention - Hypertension, fluid overload Acidosis
Why do patients with chronic kidney disease get anaemia?
- Lack of erythropoietin production from kidneys
- Lack of absorption of iron from the gut
What is the treatment for anaemia in chronic kidney disease?
Replace iron
Replace EPO if necessary (Eprex)
List some key causes of chronic kidney disease
Hypertension Diabetes Drugs Congenital e.g. ADPKD, Alport's Glomerulonephritis
What is the mechanism by which phosphate is raised in chronic kidney disease?
The kidney is unable to excrete phosphate. In addition, phosphate stimulates PTH production, which would normally reduce the levels of phosphate, but because the kidneys cannot get rid of phosphate it builds up. PTH also stimulates phosphate release from bone via osteoclast activity, so it builds up even more.
