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Post-Streptococcal Glomerulonephritis

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Overview

Also known as acute proliferative glomerulonephritis, post-streptococcal glomerulonephritis (PSGN) describes a type III hypersensitivity reaction characterised by the deposition of immune complexes consisting of complement C3 (C3) and immunoglobulin G (IgG) in the glomeruli leading to glomerulonephritis.

PSGN generally presents with an acute nephritic syndrome 1-2 weeks following infection with group A Streptococcus species (GAS), particularly Streptococcus pyogenes. It is usually self-limiting within 2-4 weeks.

Epidemiology

  • PSGN is less common in developed countries due to improved access to antibiotics and clean water supplies
  • PSGN is still common in the developing world
  • Young children are most commonly affected

Presentation

Patients may present with an acute nephritic syndrome 1-2 weeks following infection with GAS:

  • Proteinuria
    • If severe enough, this can lead to oedema which can lead to complications of fluid overload such as pulmonary oedema
  • Haematuria
  • Hypertension
  • Oliguria

Patients may also have generalised features including headaches, nausea, and malaise.

Differential Diagnoses

IgA nephropathy (IgAN)

  • In IgAN, symptoms tend to develop 1-2 days following a URTI, whereas, in PSGN, they develop 1-2 weeks after
  • Proteinuria is more common in PSGN, but haematuria may still occur in IgAN
  • Recurrence is more common in IgAN, there may be a history of previous episodes of gross haematuria

Investigations

  • Urinalysis:
    • May show red blood cells (RBCs) with or without RBC casts
    • May show protein
  • Urine microscopy and culture:
  • Urea and electrolytes (U&Es) and estimated glomerular filtration rate (eGFR):
    • May be deranged depending on disease progression
  • Throat or skin swab and culture:
    • May show the presence of GAS
    • Not commonly positive as PSGN occurs 1-2 weeks after initial infection
  • Anti-streptolysin O antibodies:
    • High or rising levels can help confirm a recent infection with GAS
  • C3 and C4 complement levels:
    • PSGN can have low C3
  • Kidney biopsy – can provide definitive diagnosis:
    • Rarely performed as most cases of PSGN are self-limiting
    • May show deposits of C3 and IgG

Management

Management is focused on preventing complications, particularly fluid overload. Most children recover without treatment. Some management options include:

  • Antibiotics – if there is evidence of a GAS infection
  • ACE inhibitors – may be required to control blood pressure
  • Haemodialysis may be needed in some cases

Complications

Complications can include:

Prognosis

In most cases, PSGN is self-resolving within 2-4 weeks with normalisation of renal function.

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