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Acute Glomerulonephritis (AGN)

Acute glomerulonephritis is a kidney disease of sudden onset characterized by inflammation of the small filtering units in the kidneys known as glomeruli.

The child with acute glomerulonephrits can present with:

  • Swelling around the eyes
  • Discoloured urine – red, tea or coffee coloured urine
  • Reduced urine volume
  • Symptoms of High blood pressure e.g. headache and convulsions

Causes of acute glomerulonephritis:

  • **Post streptococcal infection is the commonest cause of acute glomerulonephritis in children. By definition this means that there is prior infection of either the throat or skin by streptococcal bacteria.
  • Other infections that can lead to acute glomerulonephritis include other bacterial, viral or parasitic infections.
  • Other rare causes include Connective tissue disease eg systemic lupus erythematosus (SLE), eg IgA nephropathy or Henoch Schonlein Purpura.

** The commonest cause of AGN in children is post streptococcal infections; hence Post streptococcal Glomerulonephritis is also used synonymously with AGN.

Clinical features of acute Post streptococcal Glomerulonephritis.

  • There is usually a preceding history of sore throat or skin infection few days or weeks before the swelling around the eyes.
  • High blood pressure
  • The other severe but uncommon complications are :
    • hypertensive encephalopathy (very high blood pressure with fits)
    • severe kidney failure
    • pulmonary oedema (retention of excessive water in the lungs)

Investigations for the child presenting with glomerulonephritis

  • The urine is checked to detect the presence of blood and protein
  • Blood tests:
    • Kidney function test
    • Complete blood count
    • Anti streptolysin O titre, ASOT (detects antibodies against streptococcal antigen). If positive it is suggestive of a recent infection by streptococcal bacteria
    • Complement C3 & C4 level – a low level of complement C3 is expected but this usually normalizes by 6 weeks. C4 levels are normal.

Management

  • This is self limiting condition hence the management is mainly supportive depending on the severity of the condition.
  • It is important that an accurate record of the daily total fluid intake and urine output is kept Regular blood pressure and weight are also monitored
  • Fluid intake is usually restricted in the initial stages until the urine output increases. A diuretic drug eg frusemide may be used for control of hypertension & fluid overload
  • A low salt and normal protein diet is sufficient
  • A 10 day course of oral Penicillin V or erythromycin is usually prescribed to eradicate any residual streptococcal infection

Course of the disease:

  • The impaired kidney function, fluid retention and high blood pressure usually resolve by 2 to 3 weeks. Hence it is important that supportive management be given till symptoms resolve.
  • For the urinary abnormalities; urine colour usually normalizes by 3 weeks but blood detected only on urine examination can persist up till 1 year. Small amounts of protein can also be detected in the urine up till 6 months after the initial illness.
  • Kidney biopsy is only needed in patients with severe kidney failure and those whose symptoms and signs do not resolve within the expected time frame given above.

Prognosis:

  • Prognosis is very good with more than 90% of children recovering fully with no residual renal damage.
  • About 2% will develop chronic kidney disease following post strep GN and should be referred to a nephrologist for further evaluation.
  • All patients should be followed up for about 1 year to ensure that the kidney function, BP are normal and the urine is completely clear of protein and blood.
Last reviewed : 19 June 2014
Content Writer : Dr. Lee Ming Lee
Accreditor : Dr. Lim Yam Ngo
Reviewer : Dr. Aina Mariana bt. Abdul Manaf

 

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