post-streptococcal glomerulonephritis

Etiology

• may follow group-A beta-hemolytic Streptococcal infection
  • type 12 pharyngeal infection
  • type 49 skin infection
• immune complex disease with localization of streptococcal antigen-antibody complexes & complement in renal glomeruli

Pathology

• many neutrophils (renal biopsy)
• diffuse proliferative glomerulonephritis
• glomeruli are markedly enlarged & hypercellular
• electron microscopy:
  • subepithelial immune deposits or humps
  • mesangial deposits
  • crescents
• immunofluorescence demonstrates granular "lumpy-bumpy" pattern with IgG & C3

Clinical manifestations

• latent period
  • type 12 pharyngeal infection: 6-21 days
  • type 49 skin infection: 14-28 days
• suddent onset edema, hematuria, renal insufficiency
• see glomerulonephritis

Laboratory

• urinalysis
  • active urine sediment
  • proteinuria generally < 3 g/24 hours
  • fractional excretion of sodium (FENA) <1%
  • hematuria
• transiently low serum complement, CH50 & serum C3 (up to 8 weeks)
• antibodies against streptococcal antigens
  • antistreptolysin-O (ASO) in positive with pharyngeal infections
  • anti-DNAse B is positive with skin infections
  • antihyaluronidase antibodies
  • antistreptokinase antbodies
  • a change in titer indicates recent infection
• renal biopsy

Management

• no specific therapy
• supportive: control of blood pressure & edema
• penicillin for the patient & contacts may prevent new cases
• prognosis is excellent unless crescents or persistent proteinuria is present
• recovery of renal function in several weeks
  • proteinuria & hematuria resolve more slowly

More general terms

• postinfectious glomerulonephritis