8 - Pathology Flashcards
(24 cards)
Define nephrotic syndrome
Renal disease characterised by proteinuria - over 3.5g filtered in 25 hours, oedema (due to low serum albumin, low oncotic pull) and high blood cholesterol (loss of cholesterol binding proteins)
Define nephritic syndrome
Renal disease characterised by haematuria and hypertension due to blocking of filter. Proteinuria may be present too
What is glomerulonephritis?
Inflammation in glomerular tuft
What is glomerulosclerosis?
Capillary collapse, can be segmental or global, no filtration across sclerotic area
What area of the kidney is damaged in nephrotic syndrome
Podocytes/ subepithelium, as blood is filtered normally in nephrotic syndrome so selectively permeable membranes must be damaged
Name primary causes of nephrotic syndrome and can they progress to renal failure?
Minimal change glomerulonephritis - unlikely to progress to renal failure. focal segmental glomerulosclerosis-can progress to renal failure. membranous glomerulonephritis- 1/3 progress to renal failure
Names secondary causes of nephrotic syndrome
Diabetes mellitus and amyloidosis
Describe the disease process in minimal change glomerulonephritis
Widened fenestration slits on podocytes, making them unable to capture proteins so they are excreted in urine.
Describe the disease process in focal segmental glomerulosclerosis
Circulating factor damages podocytes, causing scarring so no filtration can occur across the sclerotic area
Why is transplantation not an option for patients with focal segmental glomerulosclerosis
The circulating factor will damage the new kidney
Describe the disease process in membranous glomerulonephritis
Immune complex deposits damage membrane of kidney, cause it to become inflammed and thicken
Describe how diabetes mellitus results in nephrotic syndrome
Microvascular damage due to uncontrolled glucose, mesangial sclerosis forms nodules and basement membrane thickens, allowing for proteinuria
What is haematuria caused by?
Damage to the blood vessels in kidney usually due to IgA nephropathy
Explain how nephritic syndrome leads to haematuria
Damage to the endothelium surrounding capillaries allows blood to leak into glomerulus, blocking it, blood cells excreted out
What are causes of nephritic syndrome?
Goodpasture syndrome (anti-glomerular basement membrane antibodies produced) and vasculitis (inflammation of blood vessles in glomerulus)
What is the link between IgA nephropathy and mucosal infections?
IgA secreted in mucosal membranes, if GI/ respiratory infection all IgA will deposited in the mesangium of kidneys
How does IgA nephropathy cause haematuria?
Abnormal IgA form immune complexes that are deposited in mesangium, causing a hypersensitivity reaction. This damages mesangium as it causes mesangial proliferation followed by scarring, which allows blood to leak out.
Name hereditary nephropathies
Alport syndrome and thin GBM nephropathy
Describe thin GBM nephropathy
Isolated haematuria, wont progress to renal failure, thin membrane likely to develop lesions and let blood through
Describe Alport Syndrome
X linked, abnormal collagen IV results in abnormally laminated and split GBM, progresses to renal failure. Associated with deafness.
Describe process of Goodpasture syndrome
Autoantibody to collagen IV in basement membranes in kidney only, IgG deposited without extracellular matrix.
How is Goodpasture syndrome treated?
Immunosuppresents and plasmaphoresis
Describe how vasculitis damages the kidneys
Blood vessels become inflammed, attacked by anti neutrophil cytoplasmic antibody (ANCA)
What causes different expression of immune complex mediated disease?
Podocytes/basement membrane (normally) act as barrier but immune complexes can be deposited directly into mesangium (IgA nephropathy)
Antigen on podocyte being abnormally recognised, IgG binds to it, forming immune complexes within the glomerulus - circulating immune complexes are too big to enter so are not causing damage
