Nephrology: Post strep glomerulonephritis and post inf GN

Question 1

Definition of acute post-infectious glomerulonephritis

Answer 1

Acute nephritic syndrome and diffuse proliferative GN

Typically occurs in older immunocompromised pt (diabetes, cancer, AIDS)

Question 2

Causes of acute post infectious glomerulonephritis:

Answer 2

Stap, pneumococcal meningococcal, syphilis
influenza B, mumps, rubella Coxsackie
Candida
Malaria toxoplasmosis

Question 3

Clinical presentation of post inf GN:

Answer 3

Nephritic syndrome
(haematuria, hypertension, pyuria, oliguria)

Question 4

Dx of post inf GN:

Answer 4

Urinalysis: RBC casts, pyuria
Bloods: BUN, serum Cr, complement components (low c3 with normal c4)

Biopsy if no resolution in 1 week and for ddx

Question 5

Tx of post inf GN:

Answer 5

Treat underlying cause: antibacterial antivirals etc
salt and fluid restriction
Treat hypertension

Question 6

Definition of Post strep infection

Answer 6

Glomerulonephritis caused by a strep infection. It is a diffuse proliferative infection. Typical presentation is a child 1-2 weeks post strep infection.

Question 7

Is PSGN a focal or diffuse infection? What is the difference between focal and diffuse?

Answer 7

It is a diffuse infection. Focal means only a few structures (in this case glomeruli) are affected while diffuse means all structures.

Question 8

What does proliferative mean?

Answer 8

It is hypercellular meaning it affects many cells and may be more cells that normally in the body

Question 9

Causes of post strep GN:

Answer 9

Inflammation of the glomerulus caused by immune complex deposition.

Strep infection (group A strep\ S.Pyogens). GN appear 1-2 weeks post strep infection especially in children (2-6 yrs. peak incidence)

Question 10

Strep infections can affect the throat or the skin typically. What other diseases can these complications lead on to cause?

Answer 10

Strep throat can cause rheumatic fever or post strep GN.

Skin infection (such as impetigo) can only lead to post strep GN

Question 11

Sx of PSGN:

Answer 11

Fever
Nephrotic syndrome:
haematuria (RBC casts) (microscopic)
sub nephrotic proteinuria
Oliguria
JVD
Hypertension
Mild edema (puffy eyes or generalised)
Sterile pyuria

Question 12

Dx of PSGN:

Answer 12

Lab:
- Blood: raised ESR CRP BUN
low C3
positive or negative ASO
+ve anti DNAse
- Urinalysis: haematuria, RBC casts, mild proteinuria, oliguria, sterile pyuria?

Biopsy: (typically only done if condition has not improved or suspicion of RPGN
-LN: large glomeruli, consolidated and hypercellular.
- IF/EN: lumpy bumpy appearance of subepithelial deposits between podocytes and GBM

Question 13

ASO is used to confirm strep infection. If the ASO titre is negative would that confirm they do not have PSGN?

Answer 13

No anti ASO can be negative and still be PSGN as strep skin infection causes release of cholesterol which permanently binds

Question 14

2 children present with blood in the urine post URTI. Child A with haematuria 3 days post infection. Child B 2 weeks post infection? What would the diagnosis be based on just these factors? How would you dx and tx the two patients?

Answer 14

Child A would have IgA nephropathy. Child B would have PSGN due to time taken for haematuria to occur.

Dx:
Tx:

Question 15

Tx of PSGN:

Answer 15

In children there is good prognosis and self limiting.
Supportive care
Penicillin G or V for the strep infection,
ARBs, ace inhibitors, calcium channel blockers for HTN
Low salt and low proein diet, loop diuretics for edema

Question 16

Complications of PSGN:

Answer 16

In adults could develop RPGN -> renal failure (25%)
50% of adults have reduce renal function
10% of children progress to RPGN