Pathology Of The Urinary System Flashcards
What does the site of glomerular injury determine?
A patients clinical presentation
What are the types of glomerular injury?
Primary
Secondary
What is a primary glomerular injury?
Just affecting the glomerulus
What is a secondary glomerular injury?
Systemic injury that has in turn damaged the glomerulus
What are the sites of glomerular injury?
Subepithelial
Within glomerular basement membrane
Subendothelial
Mesangial/paramesangial
Where is considered to be sub-epithelial when considering glomerular injury?
Anything that affects podocytes/podocyte side of glomerular basement membrane
Where is considered to be subendothelial when considering glomerular injury?
Inside the basement membrane
Where is mesangial/paramesagnial tissue found?
Supporting the capillary loop
What are the potential pathologies of the glomerulus?
Fluid can block
Fluid can leak
What can cause the glomerular filter to block?
Renal failure
What are the main symptoms of renal failure causing filter blockage?
Hypertensive
Haematuria
What conditions are caused by the leaking of the glomerular filter?
Proteinuria
Haemoturia
What protein is found in the urine in proteinuria resulting from the leakage of the glomerular filter?
Albumin
Do proteinuria and haemoturia occur separately or together as a result of glomerular filter leakage?
Can be either, depending on damage
What is proteinuria?
The presence of excess serum proteins in urine
What is the diagnostic criteria of proteinuria?
<3.5g filtered every 24 hours
What is presence of proteins in urine due to?
Podocyte damage
How does podocyte damage lead to proteinuria?
The widening of the fenestration slits causing protein to be leaked when it would normally not be filtered.
What can proteinuria be said to be?
A ‘less severe’ nephrotic syndrome
What is nephrotic syndrome?
When over 3.5g of proteins is filtered in 24 hours
What is the result of nephrotic syndrome?
Generalised oedema
Why does nephrotic syndrome cause generalised oedema?
As a lot of protein is being filtered, oncotic pressure is reduced
What is the most likely site of injury in nephrotic syndrome?
Podocyte/subepithelial injury
What are the common primary causes of proteinuria/nephrotic syndrome?
Minimal change glomerulonephritis
Focal segmental glomerulosclerosis
Membranous glomerulonephritis
What are the common secondary causes of proteinuria/nephrotic syndrome?
Diabetes mellitus
Amyloidosis
Why can diabetes mellitus lead to proteinuria/nephrotic syndrome?
Microvascular complications affect kidneys
When does minimal change glomerulonephritis present?
In childhood/adolesence
What happens to the incidence of minimal change glomerulonephritis (MCG) with age?
It reduces with increasing age
What does MCG cause?
Heavy proteinuria or nephrotic syndrome
What is the treatment for MCG?
Usually responds well to steriods
What is the problem with MCG treatment?
May reoccur once weaned off treatment
Does MCG progress to renal failure?
Not usually- normally purely protein loss from kidney
Why is MCG named as such?
Because when looking at the glomeruli under a light microscope, they appear to be completely normal
How can the changes in MCG be seen?
Under an electron microscope
What can be seen under a electron microscope with MCG?
Damage to podocytes is evident- widening fenestration slits, which allow protein to lead through
What is the pathogenesis of MCG?
Unknown
Why is FSGS considered to be focal?
It involves less than 50% of glomeruli on light microscopy
Why is FSGS considered to be segmental?
It involves part of the glomerular tuft
What is the fibrosis aspect of FSGS?
Scarring
When does FSGS present?
In adulthood
When does FSGS present?
Adulthood
How does the FSGS response to steroids differ from that of MCG?
It is less responsive to steroids
Why is protein present in the urine with FSGS?
Podocytes undergo damage and subsequent scarring, so protein is lost in urine
What is responsible for podocyte damage in FSGS?
A circulating factor
What evidence is there for FSGS being caused by a circulating factor?
In transplanted kidneys, the same damage occurs
Can minimal change FSGS progress to renal failure?
Yes
What is the pathogenesis of FSGS?
Unknown
What is the most common cause of nephrotic syndrome in adults?
Membranous glomerulonephritis (MG)
What does MG result from?
Immune complex deposits in the sub-epithelial space
What is the basis of MG?
Probably an autoimmune basis, however also evidence that it may be secondary
What is the autoimmune basis of MG likely to be?
Autoantibody to podocytes
What is the evidence that MG may be a secondary disease?
It is associated with other conditions
What other conditions that MG is associated with?
Particular malignancies, e.g. Lymphoma
What rule does MG follow?
The rule of thirds
What is the rule of thirds with MG?
1/3 just get better
1/3 ‘grumble along’ with proteinuria but are fine
1/3 progress to renal failure
What is shown on the micrograph of MG?
Capillary loop far too thick
Basement membrane looks specky
What is nephritic syndrome?
Renal failure due to blocking of the filter
What is the most common glomerular nephropathy’?
IgA nephropathy
When can IgA nephopathy occur?
At any age
What is IgA nephropathy characterised by?
Deposition of IgA antibody in the glomerulus
How does IgA nephropathy classically present?
With visible/invisible haematuria
What has IgA nephropathy been shown to have a relationship with?
Mucosal infections
Why does IgA nephropathy have a relationship with mucosal infections?
IgA protects mucosal surfaces
In what respects is IgA nephropathy variable?
In its histological features and course
How does the course of IgA nephropathy vary?
Some, but not all, patients have proteinuria, and a significant proportion of patients, but not all, progress to renal failure
Why does variation in the course of IgA nephropathy occur?
Unknown
What histological features may occur in IgA nephropathy?
Mesangial proliferation
Scarring
What is the treatment for IgA nephropathy?
No effective treatment
What are the hereditary nephropathies?
Thin GBM nephropathy
Alport syndrome
What is the problem with distinguishing between the hereditary nephropathies?
The two are not completely distinct, with a grey area between them
What are the features of thin GBM nephropathy?
Nephropathy Benign familial nephropathy Isolated haemoturia Thin GBM Benign course
What are the features of Alport syndrome?
X linked Abnormal collagen IV Associated with deafness Abnormal appearing GBM Progresses to renal failure
What renal symptoms can diabetes mellitus lead to?
Progressive proteinuria
Progressive renal failure
Mesangial scleorosis
What kind of damage to the kidney occurs in diabetes mellitus?
Microvascular (damages glomerulus directly)
What does mesangial sclerosis in diabetes mellitus lead to?
Nodules