Acute Poststreptococcal Glomerulonephritis Flashcards
APSGN follows infection of the throat or skin by certain nephritogenic strains of …..?
Group A β-hemolytic streptococci
Epidemiology of PSGN…. .?
Poststreptococcal GN commonly follows
> streptococcal pharyngitis during cold-weather
months and
streptococcal skin infections or pyoderma during
warm-weather months
Histology of PSGN …..?
Glomeruli appear enlarged and relatively bloodless and show a diffuse mesangial cell proliferation, with an increase in mesangial matrix
Polymorphonuclear leukocyte infiltration is common in glomeruli during the early stage of the disease. Crescents and interstitial inflammation may be seen in severe cases, but these changes are not specific for poststreptococcal GN.
Imm mmunofluorescence microscopy which pattern in PSGN
reveals a pattern of “lumpy-bumpy” deposits of immunoglobulin and complement on the glomerular basement membrane and in the mesangium
On electron microscopy, features in PSGN ….?
On electron microscopy, electron-dense deposits, or “humps,” are observed on the epithelial side of the glomerular basement membrane
PATHOGENESIS of PSGN …..?
Circulating immune complex formation with streptococcal antigens and subsequent glomerular deposition is thought less likely to be a pathogenic mechanism
Molecular mimicry whereby circulating antibodies elicited by streptococcal antigens react with normal glomerular antigens, in situ immune complex formation of antistreptococcal antibodies with glomerular deposited antigen, and complement activation by directly deposited streptococcal antigens continue to be considered as probable mechanisms of immunologic injury.
precise nephritogenic antigen(s) that cause disease
streptococcal pyogenic exotoxin (SPE) B and nephritis-associated streptococcal plasmin receptor are promising candidates
Poststreptococcal GN is most common in which age group ….?
children ages 5-12 yr and uncommon before the age of 3 yr
The typical patient develops an acute nephritic syndrome when …..?
1-2 wk after an antecedent streptococcal pharyngitis
3-6 wk after a streptococcal pyoderma
Risk of developing nephrotic syndrome in PSGN …..?
<5%
T he acute phase generally how long it lost ..?
resolves within 6-8 wk.
Although urinary protein excretion and hypertension usually normalize by 4-6 wk after onset,
persistent microscopic hematuria can persist for 1-2 yr after the initial presentation.
What happens to serum c3 levels in PSGN …?
The serum C3 level is significantly reduced in > 90% of patients in the acute phase, and
returns to normal 6-8 wk after the onset
The best single antibody titer to document cutaneous streptococcal infection is …..?
antideoxyribonuclease B level
The antistreptolysin O titer role in PSGN ….?
The antistreptolysin O titer is commonly elevated after a pharyngeal infection but rarely increases after streptococcal skin infections.
Renal biopsy should be considered in PSGN when …..?
acute renal failure,
nephrotic syndrome,
absence of evidence of streptococcal infection, or normal complement levels
hematuria and proteinuria, diminished renal function and/or a low C3 level persist more than 2 mo after onset.
