Nephritic Syndrome Flashcards
What disorder is caused by subendothelial immune complex deposits?
Membranoproliferative GN
What disorder is caused by mesangial immune complex deposits?
IgA nephropathy
Acute nephritic syndrome is characterized by the acute onset of: (6)
- Hematuria (Microscopic or macroscopic, RBC casts)
- Hypertension
- Oliguria
- Edema –usually moderate
- Mild to moderate proteinuria
- Azotemia
Diseases due to immune deposition are associated with circulating immune complexes that are planted at sites according to their:
size charge (and other affinity characteristics)
3 Causes of endothelial cell injury:
- Deposition of immune complexes in the subendothelial space
- Thrombotic microangiopathies
- Entrapment of paraproteins (in B-cell lymphoproliferative disorders, Plasma cell dyscrasias, Multiple myeloma)
Endothelial damage results in:
How does this manifest clinically?
a local inflammatory response
- Cytokines + autacoids are released
- Cytokines, autocoids + activated complement upregulate adhesion molecules on endothelial and circulating immune cells
Hematuria
What pathophysiological findings are characteristic of Membranoproliferative glomerulonephritis type I?
- Hypercellularity of the glomerular tuft
- Increased mononuclear cells within expanded mesangium + capillary lumens
- Double-contour/duplication of glomerular basement membrane (tram track)
What causes duplication of the basement membrane?
endothelium displaced by
1) immune deposits
2) infiltrating mesangial cells
What are possible presentations of MPGN type I? (5)
- Microscopic hematuria
- Non-nephrotic range proteinuria
- Nephrotic syndrome
- Acute nephritic syndrome
- Rapidly progressive glomerulonephritis
MPGN type 1 is often associated with what infection?
hepatitis C
What lab value will be low in MPGN type 1 and 2?
C3
MPGN type I progresses (slowly/rapidly) to end stage renal disease.
slowly
What is present in 80% of patients with dense deposit disease (MPGN type 2)?
C3 nephritic factor
What conditions may be associated with dense deposit disease (MPGN type 2)?
- macular deposits in the eyes
2. acquired partial lipodystrophy (loss of subcut fat in upper 1/2 of body)
In dense deposit disease (type II MPGN), what is seen on immunofluorescence? On Electron microscopy?
IF: C3, but no Ig
EM: characteristic electron-dense deposits in the GBM
Describe the Pathophysiology of immune-complex-mediated membranoproliferative
glomerulonephritis.
- complement activated via classical pathway
- leukocytes recruited
- leukocytes release proteases, etc, that damage endothelium/BMem/epithelium
- repair leads to formation of new BMem that incorporates debris
Describe the Pathophysiology of complement-mediated membranoproliferative
glomerulonephritis.
- controls of complement activation are dysregulated
- complement activated via alternative pathway
- leukocytes recruited
- leukocytes release proteases, etc, that damage endothelium/BMem/epithelium
- repair leads to formation of new BMem that incorporates debris
Most common primary glomerulonephritis worldwide:
IgA nephropathy (IgAN)
What characterized IgA nephropathy (pathologically)?
deposition of IgA-containing immune complexes predominantly in the mesangium, which results in a mesangioproliferative pattern of injury
IgA nephropathy may occur secondary to what conditions? (7)
Henoch-Schonlein Purpura Ankylosing spondylitis Dermatitis herpetiformis Celiac disease Inflammatory bowel disease Cirrhosis Psoriasis
What triggers IgA nephropathy, and how does this progress to the disease state (pathogenesis)?
- URI or GI tract infection
- IgA are produced that are under galactosylated at O-linked glycans in the hinge region of IgA1
- IgG or IgA1 antibodies recognize these O-linked glycans terminating with N-acetylgalactosamine instead of galactose
- Circulating immune complexes (CICs) deposit in the mesangium
* may result in a proliferative and occasionally necrotizing glomerulitis
________ nephritic sediment occurs within 1-2 days of infection.
synpharyngitic
Possible presentations of IgA nephropathy:
*highly variable
- Asymptomatic
- Microscopic hematuria
- Intermittent gross hematuria
- Synpharyngitic hematuria
- Proteinuria – nephrotic or non-nephrotic
- Acute glomerulonephritis
- Rapidly progressive glomerulonephritis
How does IgA nephropathy present clinically?
hypertension (often)
50% have increased serum IgA levels
increased risk for loss of renal function
Risk factors for IgA nephropathy-associated loss of renal function:
Heavy proteinuria Decreased GFR at onset Older age at onset Uncontrolled hypertension Crescents and/or tubulointerstitial fibrosis/atrophy Familial forms
What is the pathophysiology of anti-GBM disease?
- autoantibodies form against a noncollagenous portion of the α-3 subunit of type IV collagen
- antibodies (usually IgG) bind to the GBM in a linear + uniform manner
- Rapidly progressive glomerulonephritis develops, leading to kidney failure rapidly develops (due to focal glomerular necrosis and crescent formation)
What symptoms may precede or coincide with onset of renal dysfunction in Goodpasture’s disease?
Cough
dyspnea
crackles
hemoptysis
In Goodpasture’s disease, what may exacerbate pulmonary hemorrhage?
tobacco smoke
influenza
volatile hydrocarbons
How does Goodpasture’s disease present?
Rapidly progressive renal failure with azotemia (50-70%)
Anemia out of proportion to renal insufficiency
Arthritis/arthralgias common
Hypertension (~20%)
How is Goodpasture’s disease treated?
corticosteroids, plasmapheresis, and cytotoxic agents
What are “crescents”, and what do they result in?
accumulation and proliferation of cells outside the glomerular tuft
result in compression of the tuft with rapid progression to renal failure
____ crescentic glomerulonephritis is a condition characterized by >50% glomeruli affected (under light microscopy).
diffuse
What are the 4 progressive/worsening crescent appearances?
*sorry, couldn’t figure out how to word this
- segmental proliferative and necrotizing lesions
- cellular crescents
- fibrocellular crescents
- fibrous crescents
Pathogenesis of crescents:
- severe damage to capillary walls
- damage causes tears and necrosis to GBM
- RBC, WBC, fibrinogen and plasma constituents enter Bowman’s space
- mononuclear cells and parietal epithelial cells proliferate
(antibody and cell-mediated processes may be involved)
Type II Crescentic Glomerulonephritis is associated with what pattern of immune deposits?
granular
Rapidly progressive glomerulonephritis (is/isn’t) a medical emergency.
“not”–
but requires prompt dx and trx to prevent severe permanent renal damage/failure
How is Alport syndrome inherited, and what is defective?
defects in α-5 collagen type IV (COL4A5)
X-linked (but may be AR)
How do heterozygous females present with Alport syndrome? Heterozygous males?
females: hematuria + thin basement membranes
males: persistent hematuria, progressive proteinuria, ultimately ESRD (heterozygous=affected)
Both: sensorineural hearing loss, lens abnormalities, platelet defects, (rarely) esophageal leiomyomas
What would you see in a kidney biopsy from a patient with Alport syndrome?
abnormally thin basement membranes
splintering of lamina densa, “basket weave appearance”
What protein abnormality causes thin basement membrane disease, and how severe is it?
defects in α-3 or α-4 collagen type IV, which results in GBM that is uniformly reduced by half
Usually benign if heterozygous
