Paediatrics: Glomerulonephritis

2021-03-04 12:00 AM

A combination of haematuria, oliguria, oedema, and hypertension with variable proteinuria.

Glomerulonephritis

A combination of haematuria, oliguria, oedema, and hypertension with variable proteinuria.

  • Majority of cases post-infectious.
  • Usually presents 1–2wks after a URTI and sore throat.

Causes of acute glomerulonephritis

Post-infectious

  • Bacterial: streptococcal commonest, Staphylococcus aureus,
  • Mycoplasma pneumoniaSalmonella
  • Virus: herpesviruses (EBV, varicella, CMV)
  • Fungi: candida, aspergillus
  • Parasites: toxoplasma, malaria, schistosomiasis

Others (less common)

  • MPGN
  • IgA nephropathy
  • Systemic lupus erythematosus
  • Subacute bacterial endocarditis
  • Shunt nephritis

Investigations

  • Urine:

o urinalysis by dipstick: haematuria +/– proteinuria;

o microscopy—casts (mostly red cell casts).

  • Throat swab: culture.
  • Bloods:

o FBC;

o U&E, including creatinine, bicarbonate, calcium, phosphate, and

o albumin;

o ASOT/antiDNAase B;

o complement (expect low C3, normal C4);

o autoantibody screen (include ANA).

  • Renal US (urgent).
  • CXR (if fluid overload suspected).

Management

Most require admission because of fluid balance, worsening renal function, or hypertension. Treat life-threatening complications first:

  • hyperkalaemia;
  • hypertension;
  • acidosis;
  • seizures;
  • hypocalcaemia.

Otherwise supportive treatment.

  • Fluid balance:
  • weigh daily;
  • no added/restricted salt diet;
  • if oliguric, fluid restrict to insensible losses (400mL/m2) + urine
  • output;
  • consider furosemide 1–2mg/kg bd if fluid overloaded.
  • Hypertension:

o treat fluid overload;

o α-blockers and calcium channel blocker usual first choice;

Note: Do not use ACE inhibitor (may worsen renal function).

  • Infection: 10-day course of penicillin (does not affect natural history, but limits the spread of nephritogenic bacterial strains).

When to refer to paediatric nephrology unit

  • Patients with life-threatening complications (see Management).
  • Those with atypical features, including:
  • worsening renal function;
  • nephrotic state;
  • evidence of systemic vasculitis (e.g. rash);
  • normal C3 complement levels;
  • increased C4 complement levels;
  • +ve ANA;
  • persisting proteinuria at 6wks;
  • persisting low C3 at 3mths.

Prognosis

  • 95% with post-streptococcal glomerular nephritis (GN) show complete recovery.
  • Microscopic haematuria may persist for 1–2yrs.
  • Discharge from follow-up once urinalysis, BP, and creatinine are normal.