Nephrotic and Nephritic syndrome Flashcards
What are the renal limited diseases that result in glomerulonephritis?
- IgA nephropathy
- Anti-GBM disease (the kidney version of Goodpasteur’s)
- MPGN, membranoproliferative glomerulonephritis
- Renal limited vasculits (ANCA associated)
- Hemolytic-uremic syndrome
- C3 glomerulopathy/Dense deposit disease
What are the systemic diseases that can result in glomerulonephritis?
- Henoch-Schonlein purpura
- Goodpasture’s syndrome
- Lupus nephritis
- ANCA associated vasculitis
- Infection assoiated
- Post-infectious
- Endocarditis/shunt nephritis
- Cryoglobulinemia
- Immunoglobulin deposition diseases
How should the approach to a patient with possible glomerular disease begin?
- Assessment of the protein excretion in the urine
- Microscopic analysis of the urine for dysmorphic RBCs and/or RBC casts
- Biopsy can confirm suspicions
What are the primary characteristics of nephritic syndrome?
- Reduction in GFR (elevated serum creatinine)
- Active urine sediment (RBCs, WBCs and RBC casts)
- Proteinuria (usually sub-nephrotic)
- Edema
- hypertension
What is the clinical presentation of nephritic syndrome?
- Mild proteinuria, mild hematuria are possible
- More common = hematuria, dysmorphic RBC or RBC casts, proteinuria (though not the nephrotic range???)
- Proteinuria can range 200mg to 10gm a day
- Accompanied by HYPERTENSION AND EDEMA
What are the three primary systemic diseases that cause secondary nephrotic syndrome?
• Diabetes
○ Most common cause of nephrotic syndrome in adults
○ Usually present with nephrotic proteinuria, commonly microhematuria
○ Biopsy shows nodular glomerulosclerosis with mesangial expansion and thickening of GBM
○ Treatment is better glucose control, BP control and ACEI
• SLE
○ More often presents with nephritic presentation, but can cause nephrotic syndrome through a membranous histologic pattern. Treated with prednisone and mycophenolate
• Amyloidosis
○ Need free plasma light chains, serum and urine protein electrophoresis and renal biopsy
What is MPGN?
- MPGN = membranoproliferative glomerulonephritis
- Histologic pattern where there is both proliferation (mesangial proliferation in a lobar pattern) AND thickening of GBM
- Separated into type I and II
- Type I = immune complex deposits
- Type 2 = complement activation in capillary wall but no immune deposits
- Most often associated with Hepatitic C infection or some other chronic systemic infection
What is the clinical presentation and treatment of MPGN?
- A decent proportion of MPGN present with acute nephritis
- Hypertension is common early on in this disease
- HCV infection is common
- Associated with cryoglobulins, rheumatoid factor and low C3 and C4 compliment levels
- Can be associated with C3Nef or nephritic factor, which activates compliment in circulation
- Treatment = anti-HCV therapies, immunosuppression in acute nephritis presentation, treat underlying chronic infection, ecluzimab (targets compliment)
What makes a pathologist think MPGN?
- MPGN = membranoproliferative glomerulonephritis
- Light microscope = type I shows thickening of GBM, mesangial cell proliferation and a lobulated appearance of the glomerulus. C3 deposits prominent on capillary walls and in the mesangium. IgG deposits also seen
- EM = type I shows subendothelial and mesangial deposits (immune complexes)
- Type II looks similar but differs by IF because only C3 but no IgG and differs by EM by showing dense deposits of unknown etiology
What is membranous nephropathy?
- Immune mediated glomerular disease associated with immune complex deposits in the subepithelial space (between podocyte and GBM)
- Called membranous because of thick GBM on light microscopy
- Most common cause for idiopathic nephrotic syndrome in older (like above 40s) adults
What is the clinical presentation and treatment of membranous nephropathy?
- Nephrotic syndrome and edema
- Hypertension and renal failure are uncommon at presentation, but they do develop
- Compliment levels normal
- Need to look for underlying cancer of breast, lung, GI tract
- Treatment = steroids and cytotoxic drugs (cyclophosphamide), ACEI to lower proteinuria
What causes membranous nephropathy?
• Autoimmune and mediated by an antibody directed against an antigen on the podocyte
• Often M-type phospholipase A2 or PLA2 receptor
• Antibody binding initates compliment fixation and direct podocyte damage
• Complexes are then capped and shed to subepithelial space
* In about 85% of cases, membranous nephropathy is caused by autoantibodies that cross-react with antigens expressed by podocytes.
*In the remainder 15%(secondary membranous nephropathy), it occurs secondary to other disorders, including infections, tumors, SLE, inorganic salts, NSAIDs
What does a pathologist look for in dx of membranous nephropathy?
- Varies according to GBM thickening seen by light microscopy
- Cellularity is normal
- Silver dyes reveal spikes along basement membrane (new material between immune complexes)
- Must see on the subepithelial side of the basement membrane
- IF = granular depostis of immunoglobulin and C3 along GBM, typical of immune complex disease
- EM = electron dense subepithelial deposits
What is the genetic factor that is important to associate with FSGS?
• APOL-1
• Apolipoprotein
• Especially with HIV infection
* maybe hypoxic too (like in sickle cell)
How do FSGS patients present and how are they treated?
- Present with idopathic nephrotic syndrome
- May be hypertensive or have microhematuria (not like minimal change)
- Treatment = ACEI treatment to reduce protein loss and have some other effects on glomerular wall
- Prolonged corticosteroid therapy (6 months) can result in remission
- If untreated, can progress to renal failure and need transplantation
In whom would you more likely consider FSGS?
- Young, 20-40 year old African Americans
- Can be HIV associated and can be heroin associated
- Most cases are idiopathic though
What is seen by a pathologist that makes him say “that’s FSGS”?
- Light microscopy = segmental scarring (sclerosis) in some glomeruli but not all
- IF = normal with some non-specific staining of IgM and C3 in sclerotic areas
- EM = diffuse podocyte fusion consistent with capillary wall defect
What is FSGS?
- FSGS = focal segmental glomerulosclerosis
- Type of nephrotic syndrome especially common in young adults and in african americans
- Light microscopy = normal glomeruli with mixed scarred/fibrotic glomeruli
- Non-scarred glomeruli are the ones that show increased permeability to proteins
What is minimal change disease?
- Most Common cause of idiopathic nephrotic syndrome IN CHILDREN, and is named because glomeruli appear normal by light microscopy
- Common cause in adults
- IF = No immunoglobulin or complement
- EM = only foot process fusion of podocytes, reflects podocyte injury only