Acute Kidney Injury and Glomerular Disease Flashcards
What is oliguria?
Less than 500ml of urine per day, or less than 20ml/hour
What is anuria?
Less than 100ml of urine per day
What does anuria indicate?
Blockage of urine flow
What are the types of acute renal injury (AKI)?
- Pre-renal disease
- Post-renal failure
- Intrinsic renal failure
What happens in pre-renal disease?
Decreased perfusion
What happens in post-renal failure?
Obstruction
What happens in intrinsic renal failure?
Damage to kidney
What can cause pre-renal disease?
- Volume depletion
- Heart failure
- Cirrhosis
What are the types of intrinsic renal failure?
- Renal artery occlusion
- Renal parenchymal
- Renal vein occlusion
What can cause renal parenchymal failure?
- Intrarenal vascular
- Glomerulonephritis
- Ischaemic ATN
- Toxic ATN
- Interstitial disease
- Intrarenal obstruction
What can cause post-renal failure?
Urinary tract obstruction
What happens unless the cause of pre-renal AKI is recognised and treated promptly?
Acute tubular necrosis (ATN) will develop
What can cause reduced renal perfusion?
- Reduced effective ECF volume
- Impaired renal autoregulation
What can cause a reduced effective ECF volume?
- Hypovolaemia
- Systemic vasodilation
- Cardiac failure
What can cause hypovolaemia?
- Blood loss
- Fluid loss
What can cause systemic vasodilation?
- Sepsis
- Cirrhosis
- Anaphylaxis
What can cause cardiac failure?
- LV dysfunction
- Valve disease
- Tamponade
What does renal autoregulation do?
Maintains a normal perfusion over a range of systemic BP
What can cause impaired renal autoregulation?
- Preglomerular vasoconstriction
- Postglomerular vasodilation
What can cause preglomerular vasoconstriction?
- Sepsis
- Hypercalcaemia
- Hepatorenal syndrome
- Drugs
What drugs can cause preglomerular vasoconstriction?
NSAIDS
What can cause postglomerular vasodilation?
- ACE inhibitors
- Angiotensin II Antagonists
What does post-renal AKI indicate?
An obstruction to urine flow after the urine has left the tubule
What % of AKIs are accounted for by pre-renal AKI?
10%
Where can an obstruction to urine flow occur?
- Ureters (bilateral)
- Bladder
- Urethra
How can obstructions to urine flow be classified?
- Within the lumen
- Within the wall
- Pressure from outside
What can cause urine obstruction within the lumen?
- Calculi
- Clot
- Papillary necrosis
- Tumour
What tumours can cause urine obstruction within the lumen?
- Renal pelvis
- Ureter
- Bladder
Where in the lumen can stones cause obstruction of urine?
- Both renal pelves/ureters (unless only one functioning kidney)
- Neck of bladder
- Urethra
What size urinary stones do not usually pass through lumen?
>10mm
What symptoms are common with urinary stones stuck within the lumen?
- Pain
- Haematuria
What can cause obstruction to urine flow within the wall?
- Congential
- Ureteric stricture
What are the congential cuases of urine flow obstruction within the wall?
- Pelviureteric neuromuscular dysfunction
- Megaureter
- Neurogenic bladder
Does obstruction to urine flow caused by something within the wall usually cause chronic or acute kidney injury?
Chronic
What can cause obstruction to urine flow due to pressure from outside?
- Prostatic hypertrophy
- Malignancy
- Aortic aneurysm
- Diverticulitis
- Accidental ligation of ureter (during surgery
What % of AKIs do instrinsic AKIs account for?
30%
What are intrinsic AKIs?
Direct injury to kidney
What are the causes of intrinsic AKIs?
- Acute tubular necrosis (ATN)
- Glomerular and arteriolar disease
- Acute tubule-interstitial nephritis
What are the causes of acute tubular necrosis?
- Severe acute ischaemia
- Toxic acute tubular necrosis
What are the causes of severe acute tubular ischaemia?
Pre-renal causes
What happens if the fall in renal perfusion is not treated promptly in severe acute ischaemia?
Tubular necrosis results
What happens in acute tubular necrosis?
Nephrotoxins damage epithelail cells lining the tubules, and cause cell death and shedding into lumen
Are nephrotoxins endogenous or exogenous?
Can be either
When is acute tubular necrosis much more likely?
If there is reduced perfusion and a nephrotoxin
How is acute tubular necrosis identified?
- Muddy brown casts (idk wat this is)
- Fractional excretion of Na > 3%
Give 3 endogenous nephrotoxins
- Myoglobin
- Urate
- Bilirubin
Give 4 exogenous nephrotoxins
- Endotoxin
- X-ray contrast
- Drugs
- Other poisions
What other poisons can act as nephrotoxins?
- Weedkillers
- Antifreeze
*
What drugs can act as nephrotoxins?
- ACE inhibitors
- Aminoglycosides
- NSAIDs
- Gentamicin
- Angiotensin receptor blockers
Why can NSAIDs act as nephrotoxins?
- Prostaglandins normally cause vasodilation of afferent arterioles in renal autoregulation
- NSAIDs inhibit prostaglandin production (inhibit COX enzyme)
- Unopposed vasoconstriction of afferent arteriole -> reduced glomerular perfusion pressure -> AKI
How is fractional excretion calculated?
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What glomerular and arteriolar disease can cause intrinsic AKI?
Acute glomerulonephritis
What is acute glomerulonephritis?
Immune disease affecting the glomerulus
What are the types of acute glomerulonephritis?
- Primary
- Secondary
What does primary acute glomerulonephritis affect?
Only the kidneys
What happens in secondary acute glomerulonephritis?
Kidneys are involved as part of systemic process
What conditions are associated with acute glomerulonephritis?
- SLE
- Vasculitis
What is acute tubulo-interstitial nephritis?
Inflammation of kidney intersticium
What are the causes of acute tubulo-interstitial nephritis?
- Infection
- Toxin induced
What infection can cause acute tubulo-interstitial nephritis?
Acute pyelonephritis
What is acute pyelonephritis?
Ascending bacterial infection
What can cause toxin induced acute tubulo-interstitial nephritis?
Drugs
When is an AKI pre-renal?
When the kidneys are underperfused
What can cause the kidneys to be underperfused?
- Shock
- Severe vascular disease
What types of shock can cause the kidneys to be underperfused?
- Hypovolaemic
- Septic
- Cardiac
What can cause the kidneys to be underperfused in severe vascular disease?
Emboli
When is an AKI renal?
- When nephrotoxins are implicated
- Parenchymal disease
- Multisystem disease
When are nephrotoxins implicated?
- Drugs
- Sepsis
- Myoglobin
What multisystem disease can cause renal AKI?
UTI
When is an AKI post-renal?
When there is a renal tract obstruction
What is investigated in pre-renal AKI?
Cardiac failure
How can cardiac failure cause AKI?
Overloading kidney
What will be found on investigation with AKI caused by cardiac failure?
- Gallop rhythm
- Raised BP
- Raised JVP
- Pulmonary oedema
- Peripheral oedema
What are the features of pulmonary oedema on investigation?
- Basal crackles
- Dyspnoea
Where is peripheral oedema found in cardiac failure causing AKI?
- Sacral
- Ankle
What will be found on investigation with sepsis causing renal AKI?
- Pyrexia and rigors
- Vasodilation
- Warm peripheries
- Bounding pulse
- Rapid capillary fill
- Hypotension
What will be found on investigation with urinary tract obstruction causing post-renal AKI?
- Anuria
- Single functioning kidney
- History of renal stones, prostatism, or previous pelvic/abdominal surgery
- Palpable bladder
- Pelvic/abdominal masses
- Enlarged prostate (DRE)
What methods are used to investigate patients with AKI?
- Serum biochemistry
- ECG
- Urine testing
- Soluble immunological tests
- Imaging
- Histology
What will be found on serum biochemistry with AKI?
- Increased urea
- Increased creatinine
- Hyperkalaemia
- Hyponatraemia
- Hypocalcaemia
- Hyperphophataemia
What causes ECG changes in AKI?
Hyperkalaemia
What will be seen on ECG with hyperkalaemia?
- Tall T waves
- Small/absent P waves
- Increase in PR interval
- Wide QRS complex
- ‘Sine wave’ pattern
- Asystole
What urine testing is conducted when investigating AKI?
- Dipstick testing
- Microscopy
What is being looked for with dipstick testing for AKI?
- Blood
- Protein
- Leucocytes
Is proteinuria present with pre-renal AKI?
No
Is haematuria seen with pre-renal AKI?
No
Is proteinuria seen with ATN?
No
Is haematuria seen with ATN?
No
Is proteinuria seen with glomerulonephritis?
Yes, lots
Is haematuria seen with glomerulonephritis?
Yes, lots
What will be seen on microscopy with pre-renal AKI?
Hyaline cast
What is hyaline cast?
Aggregations of protein seen in concentrated urine
Is hyaline cast normal?
Yes
What will be seen on microscopy with acute tubular necrosis?
Muddy brown cast
What will be seen on microscopy with rapidly progressing glomerulonephritis?
Red blood cell cast
What is detected by soluble immunological tests with AKI?
Circulating antibodies
What ciculating antibodies may be found with AKI?
- Anti-nucleur antibodies
- Anti-neutrophil cytoplasmic antibody
- Anti-glomerular basement membrane antibodies
In what condition would anti-nucleur antibody be found circulating?
SLE
In what condition would anti-neutrophil cytoplasmic antibody be found circulating?
Systemic vasculitis
In what condition would anti-glomerular basement membrane antibodies be found circulating?
Goodpasture’s disease
What imaging is conducted when investigating AKI?
- Ultrasound
- CXR
What is being looked for on ultrasound with AKI?
- Renal size
- Hydronephrosis
- Presence of obstruction
What is being looked for on CXR with AKI?
Pulmonary oedema
What is required for histology when investigating AKI?
Biopsy
When is a biopsy obtained in AKI?
- When pre-renal and post-renal AKI have been ruled out
- A confident diagnosis of ATN cannot be made
- Systemic inflammatory symptoms or signs are present
Here come dat boi
O shit waddup
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What is treatment of AKI dictated by?
Its cause
What is the treatment for pre-renal failure?
Volume correction
How is hypovolaemia treated?
Fluid administration
How is heart failure treated?
Diuretic
How is post-renal failure treated?
Urological intervention to re-establish urine flow
How is acute tubular necrosis treated?
Treament is supportive, maintaing good kidney perfusion and avoiding nephrotoxins
When is dialysis initiated in AKI?
If the kidneys can no longer adequately excrete salt, water, and potassium
How is asymptomatic glomerular disease detected?
Incidentally, by dipstick analysis
When may asymptomatic glomerular disease be detected incidentally?
At a health check or life insurance medical
How can asymptomatic glomerular disease be detected in dipstick analysis?
Microscopy haematuria, proteinuria, or both
What is sometimes detected at the same time as asymtomatic glomerular disease?
Hypertension
What is the first investigation carried out following urine dipstick in asymptomatic glomerular disease?
Cystoscopy
Is a renal biopsy mandatory in asymptomatic glomerular disease?
No
What can cause microscopic haemtauria?
- Renal stones/tumours
- Arteriovenous malformations
- Glomerular disease
What is considered to be non-nephrotic proteinuria?
<3.5g/24hrs protein in urine
Can microscopic proteinuria be associated with conditions other than glomerulonephritis?
Yes
Who is the cutest g pig in the world?
Gypsy
What is often true of episodic macroscopic haematuria associated with glomerular disease?
It is often brown or smoky in colour, rather than red
Are clots found in macroscopic haematuria?
Very unusual
What does episodic macroscopic haematuria with glomerular disese need to be distinguished from?
Other causes of red or brown urine
Other than haematuria, what are the other causes of red or brown urine?
- Haemoglobin uria
- Myoglobinuria
- Consumption of food dyes
Is macroscopic haematuria painful or painless?
Usually painless
What is the commnest glomerular cause of macroscopic haematuria?
IgA nephropathy
What does macroscopic haematuria require?
Urological workup
What is nephrotic syndrome?
A non-specific disorder, where the kidneys are damaged, leaking large amount of protein into urine
What are the classical triad of findings in nephrotic syndrome?
- Proteinuria (>3.5g/24hrs)
- Hypoalbuminaemia
- Oedema
What is variably present in nephrotic syndrome?
- Hyperlipiaemia
- Muehrcke’s bands
What does nephrotic syndroem require for diagnosis?
Renal biopsy
How is the biopsy taken when investigating nephrotic syndrome?
Using an ultra-sound guided needle
Where is the biopsy aimed when investigating nephrotic syndrome?
At the bottom of the kidney
Why is the biopsy aimed at the bottom of the kidney when investigating nephrotic syndrome?
To make sure a piece of cortex is biopsied
Why must a piece of cortex be biopsied in nephrotic syndrome?
As there are no glomeruli in the medulla, so it would not be useful for diagnosis
What are the causes of nephrotic syndrome?
- Minimal change glomerulonephritis
- Focal segmental glomerulosclerosis
- Membranous glomerulonephritis
What is nephritic syndrome?
A collection of signs (syndrome) associated wth disorders affecting the kidneys, especially glomerular disorders, characterised by having small pores in the podocytes of glomerulus large enough to permit proteins and red blood cells
What are the features of nephritic syndrome
- Rapid onset
- Oliguria
- Hypertension
- Generalised oedema
- Haematuria with smoky brown urine
- Normal serum albumin
- Variable renal impairment
- Urine contains blood protein and red blood cell casts
Describe the onset of nephrotic syndrome
Insidious
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Describe the onset of nephritic syndrome
Abrupt
Is there oedema in nephrotic syndrome?
Yes, ++++
Is the oedema in nephritic syndrome?
Yes, ++
What happens to BP in nephrotic syndrome?
No change
What happens to JVP in nephrotic syndrome?
Same or decreasd
What happens to BP in nephritic syndrome?
Increased
What happens to JVP in nephritic syndrome?
Increased
Is there proteinuria in nephrotic syndrome?
Yes, ++++
Is the proteinuria in nephritic syndrome?
Yes, ++
Is there haematuria in nephrotic syndrome?
May or may not occur
Is there haematuria in nephritic syndrome?
Yes, +++
Are there red cell casts in nephrotic syndrome?
No
Are there red cell casts in nephritic syndrome?
Yes
What happens to serum albumin in nephrotic syndrome?
Decreased
What happens to serum albumin in nephritic syndrome?
Same or slightly reduced
What does rapidly progressive glomerulonephritis describe?
A clinical situation in which glomerular injury is so severe that renal function deteriorates over days
How may a patient present with rapidly progressive glomerulonephritis?
As a uraemic emergency, with evidence of extrarenal disease
What is rapidly progressive glomerulonephritis associated with?
Crescenteric glomerulonephritis
What is required for diagnosis of rapidly progressive glomerulonephritis?
Renal biopsy
What is the natural course of many forms of glomerulonephritis?
Slowly progressive renal impairment, including;
- Hypertension
- Dipstick abnormalities
- Uraemic syndrome
What is chronic renal failure often associated with?
Small, smooth, shrunken kidneys
What is the problem with biopsies in chronic renal failure?
- They are hazardous
- Unlikely to produce diagnostic material
What are the symptoms of chronic renal failure?
- Tiredness and lethargy
- Breathlessness
- Aches and pains
- Sleep reversal
- Nocturia
- Restless legs
- Itching
- Chest pains
- Seizures and comas