MedEd Flashcards
what is AKI
rapid decline in renal function
what is CKD
impaired renal function for >3months
what are features of AKI
failure to maintain homeostasis of:
fluid - oliguria, volume overload
electrolytes - hyperkalaemia
acid-base - metabolic acidosis
what can causes of AKI be sorted into
pre-renal
renal
post-renal
what are causes of pre-renal AKI
failure of perfusion
- hypovolaemia (bleeding)
- reduced cardiac output (HF, LF, sepsis)
what are causes of renal AKI
drugs (ACEi, NSAIDs, aminoglyclosides) vascular glomerular tubular (ischaemia, rhabdomylosis) interstitial
what are post-renal causes of AKI
obstruction
- BPH
- kidney stones
- blocked catheter
- malignancy
what are vascular causes of AKI
large vessel (renal artery/vein obstruction, HTN, vasculitis) small vessel -HUS -TTP -DIC -vasculitis
what is HUS
triad of
1 microangiopathic haemolytic anaemia
2 AKI
3 thrombocytopenia
what is the main cause of HUS
gastroenteritis with e coli
what is the aetiopathophysiology of HUS
gastroenteritis (ecoli) releases toxins which cause endothelial damage, this leads to thrombosis, platelet consumption and fibrin strand deposition
RBCs get cut up by fibrin strands and under go haemolysis
what are features of HUS on presentation
abdo pain and dysentry
AKI (N+V, oliguria, haematuria, proteinuria)
bleeding due to thrombocytopenia
fatigue due to MAHA
what is the aetiopathophysiology of TTP
deficiency of protein which cleaves vWF
large vWF multimers form
platelet aggregation and fibrin deposition occurs which can cause microthrombi in the kidneys
what is TTP
1 microangiopathic haemolytic anaemia
2 AKI
3 thrombocytopenia
4 fluctuating CNS signs
1. A young woman presents after a seizure. She is noted to have a fever and icterus. Her urine output is low. The most likely diagnosis is: A) Haemolytic Uraemic Syndrome B) Renal stone C) Thrombotic Thrombocytopenic Purpura D) Hepatic failure E) Polycystic kidney disease
TTP
what are consequences of glomerulonephritis
loss of barrier function
loss of filtering capacity
what are features of loss of barrier function
- proteinuria
- haematuria
what are features of loss of filtering capacity
-reduced excretion which causes accumulation of waste products
what are causes of glomerulonephritis
1 IgA nephropathy 2 Henoch Schonlein Purpura 3 Anti-GBM (goodpastures) 4 post-strep glomerulonephritis 5 pauci-immune
what features are present with IgA nephropathy
days following URTI
increased IgA immune complex formation
episodic haematuria
what features are present with HSP
systemic variant IgA nephropathy
haematuria
purpuric rash on extensor surfaces commonly in legs
polyarthritis
what features are present with anti-GBM (goodpastures)
autoantibodies to Type IV collagen (GBM & lung)
haematuria
haemoptysis
what features are present with post-strep glomerulonephritis
post strep or skin infection
strep antigens are deposited at the glomerulus which leads to immune complex formation
nephritic syndrome
what features are present with pauci immune
ANCA
associated vasculitis or limited to kidney
what is the most common cause of glomerulonephritis
pauci immune
what do anti-GBM antibodies bind to in the lungs
alveolar basement membranes
what is used to treat proteinuria in glomerulonephritis
ACEi or ARBs
why do ACEi or ARBs work for treating proteinuria
angiotensin II constricts afferent and efferent arterioles (but efferent preferentially), this build up of pressure increases pressure and so more protein is filtered through causing proteinuria
ACEi or ARBs reduce intraglomerular pressure be inhibitiing angiotensin IIs vasoconstriction on the efferent arteriole which reduces pressure and filtration of protein
what is the most common renal cause of AKI
acute tubular necrosis
what causes acute tubular necrosis
ischaemia
nephrotoxins
what are different types of nephrotoxins
drugs
myoglobulinaemia (rhabodomyolysis)
haemaglobinuria
how does ischaemia cause AKI
ischaemia leads to tubular cell injury called acute tubular necrosis
this leads to obstruction of tubular by debris which causes a decrease in GFR
what are the phases of AKI caused by ischaemia
1 initiation
-acute decrease in GFR, high Cr and urea
2 maintenance
-sustained decrease in GFR, normal Cr and high urea
3 recovery
-tubular function regenerates, increased urine volume and low urea and creatine
what causes rhabdomylosis
ischaemia, trauma, drugs which causes skeletal muscle breakdown
what is released in rhabdomylosis
lots of myoglobin which causes dark urine
lots of potassium
lots of CK
what is seen in the urine in rhabdomylosis
blood on dipstick but no RBCs on microscopy
urinary myoglobin
what metabolic disturbances can cause rhabdomyolysis
hypokalaemia
hypophosphataemia
what is myeloma
malignant disease of bone marrow plasma cells with clonal expansion of plasma cells which leads to monclonal paraprotein production
what is the mneumonic for features of myeloma
CRAB
Calcium - high
Renal failure (acute/chronic) with high urea and creatinine
Anaemia
Bone - osteolytic bone lesions which present as pain or fracture
why does renal failure occur in myeloma
high calcium
free light chains of paraprotein are deposited in the kidneys causing inflammation
what are common nephrotoxins
NSAIDs aminoglycosides (gentamicin, streptomycin) contrast agents ACEi and ARBs immunosuppressants (methotrexate)
what causes interstitial nephritis causing AKI
lymphoma
tumour lysis syndrome following chemo
- A 53 year old man suffers a ruptured aortic aneurysm and is rushed into theatre. He undergoes a successful operation and is recovering on the wards. 1 day after the operation he becomes oliguric with elevated urea and creatinine. After 1 week his urine output increases but his GFR remains low at 30ml/min.
1 rhabdomyolysis 2 HUS C Nephrotoxic agent 4 TTP 5 Acute tubular necrosis
Acute tubular necrosis
- A 17 year old student presents to A&E with a 6 day history of sore throat and flu-like symptoms. He know has frank haematuria, swelling of his ankles and poor urine output..
1 IgA nephropathy 2 HUS 3 Post-strep glomerulonephritis 4 TTP 5 HSP
IgA nephropathy
post URTI
- A 84 year old woman is found on the floor of her flat by her neighbour. She had a fall 3 days prior to her ‘rescue’ and had been unable to get up or raise the alarm. At hospital, she is assessed and found to have acute kidney injury.
A. Rhabdomyolysis B. Myeloma C. Nephrotoxic agent D. Polycystic kidney disease E. Acute tubular necrosis
A. Rhabdomyolysis
- A 79 year old man presents to A&E after his GP has found deranged U&Es and raised creatinine on routine blood work. He has a history of back pain over the last few months and says that he has been very tired recently.
A. Nephrotoxic agent B. Diabetes mellitus C. Post streptococcal glomerulonephritis D. Rhabdomyolysis E. Myeloma
E. Myeloma
- A 10 year old girl presents to A&E with irritability, abdominal pain and reduced urine output. Her parents says she has had diarrhoea for the last few days.
A. IgA nephropathy B. HUS C. Post streptococcal glomerulonephritis D. TTP E. Henoch Schonlein Purpura (HSP)
B. HUS
often follows e coli toxin
aetiology of nephrotic syndrome
impaired glomerular filtration leads to proteinuria
due to low protein levels in the blood (hypoalbuminaemia) water is drawn into soft tissues (oedema)
liver attempts to compensate for producing more LDL and VLDL which causes hyperlipidaemia
what is the triad of nephrotic syndrome
proteinuria >3.5/24hrs
low albumin <30g/l
oedema
what is nephritic syndrome
more severe glomeruli damage which leads to leakage of larger proteins and more damage (red cell casts)
haematuria is present
what is nephritic syndrome common in
glomerulonephritis
what is the triad of nephritic syndrome
proteinuria
haematuria
oedema
what is a characteristic features of nephritic syndrome
red cell cast - glomerular damage
what are common primary causes of nephrotic syndrome
membranous
minimal change
focal segmental glomerulosclerosis
mesangiocapillary glomerulonephritis
what are common secondary causes of nephrotic syndrome
diabetes
SLE
amyloid
HBV/HCV
1. A 17 year old patient is referred by his GP after presenting with periorbital oedema. The patient noticed the oedematous eyes 3 days ago, but reports feeling unwell since a throat infection 3 weeks ago. Urine dip is positive for protein and blood. The mostly likely diagnosis is A) nephrotic syndrome B) nephritic syndrome C) renal failure D) glomerulonephritis E) Acute tubular necrosis
glomerulonephritis
patient presents with nephritic syndrome however the diagnosis or cause is post strep glomerulonephritis
A 22 year old woman is found to have ankle oedema and +++ protein. BP is 120/80. The most useful diagnostic investigation is: A) FBC B) Urine albumin: Creatinine ratio C) Echocardiography D) Renal US E) Renal biopsy
E) Renal biopsy
what is the treatment for diabetic nephropathy
ACEi or ARBs
what are the two biggest causes of CKD
HTN
DM
A 75M with known severely impaired renal function presents with palpitations and vomiting. What is the likely cause of his symptoms?
A) Hypercalcemia B) Hyponatraemia C) Hyperkalemia D) Atrial Fibrillation E) Hyperparathyroidism
Hyperkalemia
A 70M with known severely impaired renal function presents in a confused state. On listening to his chest the medical student hears a strange rubbing sound. What is the underlying cause of this finding?
A) Hypercalcemia B) Hyponatraemia C) Hyperkalemia D) Atrial Fibrillation E) Hyperuraemia
Hyperuraemia
A 70M with known severely impaired renal function presents in a confused state. The same gentleman becomes short of breath and the X-ray reveals bats wing shadowing. What treatment does he need?
A) Sit up and high flow oxygen B) Venous vasodilator ( eg diamorphine) C) Furosemide IV D) Dialysis E) All of the above
All of the above
what are complications of AKI
uraemia volume overload hyperkalaemia hyperphosphataemia metabolic acidosis CKD
what does uraemia cause
pericarditis and a pericardial rub
how does hyperuraemia occur in AKI
amino acids are broken down to ammonia (toxic) which goes to the liver and is converted to urea
urea should be excreted by kidney but if there is reduced function levels rise
what is the majority of potassium found
in the cells
how is most potassium excreted
in the urine
what does potassium excretion depend on
adequate sodium delivery to distal convoluted tubule
for exchange of sodium resorption and potassium excretion
what are symptoms of hyperkalaemia
fatigue or weakness numbness or tingling N+V chest pain palpitations
how does volume overload occur in AKI
kidney cant excrete fluid
fluid builds in circulation
what are signs of volume overload
oedema (pulmonary + peripheral)
- swollen feet
- SOB + crepitations
- HTN
- raised JVP
how does metabolic acidosis present in AKI
rapid breathing (respiratory compensation) confusion
how is AKI managed
1 Assess volume + potassium -OE (BP, JVP, cap refill) -ABG -ECG for hyperkalaemia 2 aim for euvolaemia -fluids -fluid restriction 3 stop nephrotoxins -NSAIDs -ACEi -aminoglycosides 4 treat underlying cause
what does insulin do to potassium
stimulates intracellular uptake of K+
what features of hyperkalaemia on ECG
tall tented t waves
absent p waves
widening QRS
what is cardioprotective against hyperkalaemia
10ml 10% calcium gluconate
what should be given to reduce hyperkalaemia if patient is acidic
IV sodium bicarbonate
what should be given to treat pulmonary oedema
sit up and high flow oxygen
venous vasodilator
furosemide IV
name a venous vasodilator
diamorphine
what is the mneumonic for indications of dialysis on AKI
AEIOU
Acid-base disturbance -severe metabolic acidosis (pH <7.2 or BE <10) Electrolytes -persistant hyperkalaemia >7 Intoxication -drugs (BLAST: barbiturates, lithium, alcohol, salicylates, theophyline) Overload of volume -refractory pulmonary oedema Uraemia -encephalopathy or pericarditis
what is the def of CKD
impaired renal function for >3months based on abnormal structure or function
what is a normal GFR
> 90ml/min/1.73^2
what are the stages of CKD
1 kidney damage - normal GFR 2 kidney damage - mildly decreased GFR 3 decreased GFR 4 severely decreased GFR 5 end stage renal disease
what GFR is associated with stage 2 CKD
60-89
what GFR is associated with stage 3 CKD
30-59
what GFR is associated with stage 4 CKD
15-29
what GFR is associated with stage 5 CKD
<15 or dialysis
what is the most common cause of CKD
diabetes