Description

• Acute glomerulonephritis (GN) is an inflammatory process involving the glomerulus of the kidney, resulting in a clinical syndrome consisting of hematuria, proteinuria, hypertension, and renal insufficiency.
• Acute GN may be 1 of many primary diseases, or it may present as part of a systemic disease:
  • Postinfectious GN
  • IgA nephropathy–Henoch Schönlein purpura
  • Antiglomerular basement membrane disease (anti-GBM disease)
  • Antineutrophil cytoplasmic antibody (ANCA)-associated GN
  • Membranoproliferative GN (MPGN)
  • Lupus nephritis
  • Cryoglobulin-associated GN
• Clinical severity ranges from asymptomatic microscopic or gross hematuria to a rapid loss of kidney function (rapidly progressive GN [RPGN]).

ALERT
Urgent investigation and treatment are required to avoid irreversible loss of kidney function.

Epidemiology

• Postinfectious GN:
  • Most commonly follows group A β-hemolytic Streptococcus infection, but can occur as a result of other infections
  • Onset occurs 1–3 weeks after an infectious process (throat or skin).
  • Accounts for 80% of acute GN in children
• IgA nephropathy:
  • Most common form of primary acute GN
  • Occurs mainly in the 2nd and 3rd decades
  • Male > Female (3:1)
  • Incidence differs geographically: Asia > US
• Anti-GBM disease:
  • Also known as Goodpasture disease
  • A noted cause of the pulmonary–renal syndrome
  • Occurs most commonly in the 2d or 3rd decade
  • Male > Female (6:1)
• ANCA-associated GN:
  • Uncommon: Often has a relapsing and remitting course
  • 3 disease presentations:
    • Wegener granulomatosis
    • Churg-Strauss disease
    • Microscopic polyangiitis
  • Older patients are more commonly affected, although this GN can affect any age group.
• MPGN:
  • May be primary or secondary
  • May present in the setting of a systemic viral or rheumatic illness
• Lupus nephritis:
  • 30–70% of systemic lupus patients will have renal involvement.
• Cryoglobulin-associated vasculitis:
  • 80% of cases are associated with hepatitis C infection.

Risk Factors

• Epidemics of nephritogenic strains of streptococci are triggers for postinfectious GN.
• Hepatic cirrhosis and celiac disease place patients at risk for IgA nephropathy.
• Anti-GBM disease has been associated with influenza A infection and inhaled hydrocarbon solvent exposure.
• ANCA-associated GN is increased in settings where there is increased silica exposure (i.e., earthquakes and farming).
• Infection with hepatitis B and/or C are known to be associated with MPGN.
• Infection with hepatitis C is a risk factor for developing cryoglobulinemic GN.
• Mutations in alternate complement pathway genes are associated with MPGN.

Genetics
Genetic factors are likely to play a role in susceptibility to many of the acute GNs, although these have not been sufficiently defined to be useful clinically.

General Prevention

Early detection is paramount.

Etiology

• In general, an immunologic mechanism triggers inflammation and proliferation of glomerular tissue.
• Postinfectious GN: Host immune reaction to nephritogenic strains of streptococci is trigger.
• IgA nephropathy: Relates to an abnormal glycosylation of IgA
• Anti-GBM disease: Caused by autoantibodies that target type IV collagen of basement membranes
• ANCA-associated GN: Autoantibodies against neutrophil granules are involved in the pathogenesis.
• MPGN: An immune or genetic etiology is presumed, which triggers renal deposits and inflammation.
• Lupus nephritis: An immune complex-mediated glomerular disease
• Cryoglobulin-associated GN: An immune etiology is presumed, but not clearly defined.