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Renal Week 2 > Nephrotic Syndrome II > Flashcards

Nephrotic Syndrome II Flashcards

1
Q

What are some nephrotic syndromes that target podocytes?

A
  • Minimal change disease
  • Focal segmental glomerulosclerosis

can be idiopathic or secondary

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2
Q

How does minimal change disease present?

A
  • recent onset of facial and lower extremity edema
  • normal BP
  • low albumin
  • normal BUN and creatinine (i.e. normal renal function)
  • 3+ proteinuria
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3
Q

What range would the spot urine protein creatinine ratio be in minimal change disease (or any nephrotic syndrome)?

A

10+

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4
Q

What patient population is commonly affected by MCD?

A

bimodal age distribution (very young and very old). Most common cause of nephrotic syndrome in children

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5
Q

What patient population with MCD is most likely to suffer from AKI (ARF)?

A

mostly adults over 40. But for the most part kidney function is normal in MCD

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6
Q

What is the suggested etiology of MCD?

A

unclear but some suggest that T cells release a circulating permeability factor that promotes podocyte damage

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7
Q

What are the secondary causes of MCD?

A
  • Malignancy (Hodgkin’s)
  • Drugs (NSAIDs, interferon alfa)

most commonly idiopathic

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8
Q

What are some supportive measures used to treat MCD?

A
  • Control blood pressure: ACEI/ARB* (even though not elevated to decrease proteinuria)
  • Treat hyperlipidemia
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9
Q

What are some disease modifiers used to treat MCD?

A

Oral glucocorticoids: the cornerstone of therapy.

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10
Q

Is the response to glucocorticoids better seen in children or adults?

A

Response in children can be seen within few weeks, but in adults it might take longer up to months.

Excellent response to steroid in children (>90%).

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11
Q

What should you do if a patient doesnt respond to treatment for MCD?

A

If pt. does not respond to steroid look for other cause of NS.

One possibility might be that actual disease is FSGS, and because FSGS is focal and segmental distribution. Bx might have missed the affected tissue.

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12
Q

Is recurrence common with MCD?

A

Yes in children and adults

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13
Q

How does FSGS present?

A
  • lower extremity edema
  • BP elevated
  • creatinine elevated (renal impairment)
  • albumin low
  • urine protein creatinine ratio around 8
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14
Q

Patient population for FSGS?

A

more middle aged

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15
Q

T or F. The proteinuria in FSGS is not selective

A

T. While in MCD it is highly selective for albumin

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16
Q

Is there renal dysfunction in FSGS?

A

Yes, 50% of patients with FSGS develop end-stage kidney disease within 10 years of diagnosis.

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17
Q

What is Supar?

A

soluble urokinase-type plasminogen activator receptor that is secreted by white cells and goes into the glomerular capillary wall and binds to an intern that anchors podocytes to the GM and releases them causing primary FSGS

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18
Q

What is a potential treatment for FSGS?

A

plasmapheresis to remove the Supar factor

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19
Q

What are the hereditary secondary causes of FSGS?

A

Familial: Mutations in genes for A-actinin-4 (AD), Podocin (AR), and TRPC6 (AD)

Apolipoprotein L1 gene (APOL1)

or partial kidney mass loss (not hereditary)

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20
Q

What infections can cause secondary FSGS?

A

HIV, Parvo virus

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21
Q

What drugs can cause secondary FSGS?

A

Pamidronate,
Heroin,
Lithium

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22
Q

A sequence variant in the apolipoprotein L1 gene (APOL1) on chromosome 22 appears to be strongly associated with an increased risk of FSGS and renal failure in what patient population?

A

individuals of African descent.

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23
Q

Why has the mutation in APOL1 survived?

A

it provides immunity against trypanosoma induced sleeping sickness

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24
Q

What are the subtypes of FSGS?

A

Collapsing – 11%; heavier proteinuria; worst renal survival

Cellular – 3%

Tip – 17%; heavier proteinuria; more likely to obtain remission

Perihilar – 26%

Not otherwise specified – 42%

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25
Q

T or F. Immunofluorescence is a good way to differentiate between MCD and FSGS

A

F. Both are negative and don’t detect specific fluorescent antibodies

26
Q

What are the supportive treatments for FSGS?

A

Control blood pressure: ACEI/ARB

Treat hyperlipidemia

27
Q

What are the disease modifier treatments for FSGS?

A

Long-term corticosteroids most commonly used but the response is usually poor so others are needed.

28
Q

What are some other treatment options for FSGS?

A

Calcineurin inhibitors (Cyclosporine or Tacrolimus)

29
Q

Steroid sensitivity with nephrotic syndromes is important. A podocyte related NS that responds well to steroids is likely to be what?

A

Minimal change (good prognosis)

30
Q

Why do some think that MCD and FSGS are just different clinical spectra of the same disease?

A

Several reasons:

Some cases diagnosed as MCD might be actually FSGS. Which was not diagnosed because of sampling error during Bx because FSGS is focal.

In children repeated relapse of MCD can cause renal injury can lead to development of FSGS.

Non-scarred glomeruli in FSGS resemble glomeruli of MCD, in both cases we will see foot process effacement.

Both cases leads to heavy proteinuria associated with loss of glomerular charge barrier. However it is selective in MCD and non-selective in FSGS.

31
Q

What are nephrotic syndromes that target the sub-epithelial space?

A
  • Membranous nephropahty

- Post-infectious GN

32
Q

What is the most common cause of nephrotic syndrome in Caucasian adults?

A

membranous nephropathy (peak between 40s and 60s)

33
Q

T or F. Membranous nephropathy is more common in women

A

F. More in men

34
Q

Does Membranous nephropathy ever spontaneously resolve?

A

Yes, in about 30% of cases. But about 40% lead to progressive renal failure and the other 30% will persist with proteinuria and have variable renal dysfunction

35
Q

Membranous nephropathy can be primary or secondary. What are some infective causes of MN?

A
  • Hep B
  • Syphilis
  • Malaria
36
Q

What are some autoimmune causes of MN?

A

SLE

sickle cell disease

37
Q

What are some drug causes of MN?

A

penicillamine
captopril
NSAID
gold

38
Q

What are some malignancies causes of MN?

A
  • lung and colon cancer
  • melanoma

Elderly patients when Dx with membranous nephropathy should be evaluated for malignancy.

39
Q

Other secondary causes of MN?

A

complement deficiencies (particularly C2),

40
Q

What are the two theories for generation of MN?

A

1) Filtered “Cationic” Antigen

2) Autoimmunity Model

41
Q

What is the filtered cationic antigen theory?

A

In filtered Ag theory, Ag from circulation passes through the endothelium and GBM and get deposited in subepithelial space. This deposition is followed by localization of Ab, activation of complement and leading to nephritis.

Example would be PSGN
In locally generated Ag theory autoAb develops against a local Ag.

Examples are M-type phospholipase A2 receptor which is associated with primary MN and NEP in congenital MN

42
Q

What is the autoimmune model theory?

A

“Locally generated antigen” and filtered autoantibody

  • M-type phospholipase A2 receptor, (PLA2R), in primary MN
  • Neutral Endopeptidase, NEP: target Ag in congenital MN
43
Q

Whats is PLA2R?

A

PLA2R is expressed by podocytes in normal human glomeruli and was co-localized with IgG4 in immune deposits in glomeruli of patients with idiopathic MN

Serum samples from 26 of 37 patients (70%) with idiopathic but no secondary MN had autoantibodies to the M type phospholipase A2 receptor (PLA2R)

44
Q

What is the main clinical use of PLA2R?

A

Since its discovery PLA2R become very useful in clinical use. It is commonly present in primary MN and helps to diffrentiate between primary and secondary MN.

CONCLUSIONS
A majority of patients with idiopathic membranous nephropathy have antibodies against a conformation-dependent epitope in PLA2R. PLA2R is present in normal
podocytes and in immune deposits in patients with idiopathic membranous nephropathy, indicating that PLA2R is a major antigen in this disease.

45
Q

What are the risk factors for renal progression (loss of renal function) in MN?

A
  • Male gender
  • > 10 g/24 hours proteinuria
  • HTN
  • Azotemia
  • Tubulointerstitial fibrosis
  • Glomerulosclerosis
46
Q

MN

A

LM: diffuse capillary wall thickening (SPIKES on sliver stain)

IF: Granular along GBM

EM: subepithelial deposits along GBM

47
Q

How is Membranous nephropathy treated?

A

Usually depends upon degree of proteinuria

Cutoff is 4 gm

48
Q

How do you treat MN if proteinuria is less than 4 gm?

A

ACEIs and ARBs only

treatment is long

49
Q

How do you treat MN if proeinuria is more than 4 gm?

A

Try ACEIs/ARBs initially for a few months to try to bring down the proteinuria

Cytotoxic agents

  • Steroid
  • Calcineurin inhibitors
50
Q

How does Post-infectious GN present?

A
  • Recent onset of dark color urine, weight gain, decreased urine output
  • signs of fluid retention
  • elevated BP
  • recent upper respiratory tract infection
  • elevated creatinine high and albumin low
  • urine protein creatinine ratio about 4

-urinalysis more consistent with nephritic picture (many RBCs)

51
Q

What complement proteins are low in PIGN?

A

C3 is low, C4 is normal (indicates alternative pathway activation)

Low level cryoglobulinemia is also frequent

52
Q

What is PIGN usually associated with?

A

Usually associated with recent infection: Upper respiratory tract, Skin, Sepsis

and gross hematuria (team or cold-colored) urine

53
Q

What other disease causes presentation of dark urine after an upper respiratory infection?

A

IgA nephropathy (will happen within days however). In PIGN, takes 2-3 weeks

54
Q

What patient population is PIGN common in?

A

Most frequent in school-age children with M:F ratio 2:1

55
Q

T or F. Anti-streptolysin O titers are usually elevated with a preceding throat infection in PIGN.

A

F. Anti-hyaluronidase and anti-DNAse B titers are more common with preceding skin infections

56
Q

How is PIGN treated?

A

● No specific therapy; treatment of underlying infection as appropriate

● Gentle diuresis may be required for comfort

● Hypertension should be aggressively treated, especially in children, in whom hypertensive
seizures may occur

● Supportive dialysis as necessary

57
Q

What is the prognosis of PIGN?

A

● Complete resolution of hematuria/proteinuria may take months to years

● Renal prognosis favorable in children except with severe acute disease

● Up to 40% of adults develop chronic azotemia

58
Q

MCD

A

Light microscopy: Normal

Immunofluorescence microscopy: Normal (negative)

Electron microscopy: Podocyte foot process fusion (effacement)

59
Q

FSGS

A

Light microscopy: “scarring” Obliterated capillary lumen
Areas of adhesion to Bowman’s capsule

Immunofluorescence microscopy: Normal (negative)

Electron microscopy: Podocyte foot process fusion (effacement)

60
Q

MN

A

Light microscopy: diffuse thickening of the glomerular basement membrane with essentially normal cellularity

Immunofluorescence microscopy: fine granular staining with IgG and complement

Electron microscopy: subepithelial deposits

61
Q

PIGN

A

Light: proliferation, inflammation

IF: Granular deposition of C3 or IgG

EM: subepithelial humps

Renal Week 2 (13 decks)

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