Glomerulonephritis, Acute

Basics

Description

  • Acute glomerulonephritis (GN) is an inflammatory or immune-mediated process involving the glomerulus of the kidney, resulting in a clinical syndrome consisting of sudden-onset of hematuria, proteinuria, and renal insufficiency.
  • Acute GN may be caused by primary glomerular disease or secondary to systemic disease.
  • Clinical severity ranges from self-limited asymptomatic microscopic or gross hematuria to a rapidly progressive loss of kidney function over days to weeks.
ALERT
Urgent investigation and treatment are required to avoid irreversible loss of kidney function and subsequent progression to chronic kidney disease and end-stage renal disease.

Epidemiology

  • Infection-related GN
    • Postinfectious GN most commonly manifests children and occurs about 2 weeks after resolution of group A β-hemolytic Streptococcus infection.
    • Can also occur as a result of other bacterial infections, such as infective endocarditis, VP shunt nephritis, or less commonly with viral, helminthic, or parasitic infections
  • IgA nephropathy
    • Most common primary GN in the world
    • Most common in the 2nd and 3rd decades
    • Incidence differs geographically: Asia > United States
    • HSP, the form with extrarenal manifestations, typically occurs in children <10 years old.
  • Anti-GBM disease
    • Goodpasture syndrome: a notable cause of pulmonary–renal syndrome
    • Peak distribution in 3rd and 6th decades
  • ANCA-associated GN
    • Often has a relapsing and remitting course
    • Four disease presentations:
      • Granulomatosis with polyangiitis (GPA), formerly Wegener granulomatosis
      • Microscopic polyangiitis (MPA)
      • Isolated pauci-immune GN—when isolated to kidneys
      • Eosinophilic GPA, formerly Churg-Strauss disease—GN relatively common but renal involvement rarely severe
  • MPGN
    • May be primary or secondary to systemic diseases
    • Epidemiology varies depending on the mechanism of injury and is more often a subacute or chronic presentation.
  • Lupus nephritis
    • About 60% of systemic lupus erythematosus patients will have renal involvement.
    • Incidence of lupus nephritis is higher among black and Hispanic populations in comparison to white populations.
    • 6 classes
      • Minimal mesangial disease
      • Mesangial proliferation
      • Focal proliferative (active) and/or sclerosing (chronic) disease
      • Diffuse segmental or global proliferative (active) and/or sclerosing (chronic) disease
      • Membranous lupus nephritis
      • Advanced sclerosis lupus nephritis
  • Cryoglobulin-associated vasculitis
    • 80% of cases with hepatitis C virus (HCV) infection
    • May also be associated with autoimmune disease or dysproteinemia

Prevalence

  • In patients >65 years of age, with an average age of 75 years, about 1.2% of people are affected by either primary or secondary GN.
  • In patients between the ages of 37 and 65 years, GN was much less commonly seen, with only about 0.12% of people affected by either primary or secondary GN (1).
  • The incidence and prevalence of GN in children is unknown. Acute postinfectious GN is the most common type, but has diminished over the years.

Etiology and Pathophysiology

  • Systemic and/or local immune activation causes glomerular injury.
  • Immune complex mediated: antigen–antibody formation and deposition in the kidneys; immune complexes are seen on immunofluorescence.
    • Postinfectious GN
    • IgA nephropathy
    • MPGN
      • Cryoglobulin-associated GN
    • Lupus nephritis
  • Direct antibody-mediated injury, linear staining on immunofluorescence
    • Anti-GBM disease
  • Pauci-immune GN, not seen on immunofluorescence staining
    • ANCA-associated GN
  • Alternative complement pathway dysregulation
    • C3 glomerulopathy

Risk Factors

  • Epidemics of nephritogenic strains of streptococci are triggers for postinfectious GN.
  • Anti-GBM disease has been associated with prior pulmonary injury and inhalation exposures, such as hydrocarbon solvents.
  • ANCA-associated GN may be drug induced (e.g., hydralazine, levamisole-contaminated cocaine) and is also associated with environmental exposures such as silica.
  • Hepatitis B is associated with MPGN. Hepatitis C is associated with both MPGN and cryoglobulinemic GN.

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