Paediatrics: Glomerulonephritis

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 pneumonia, Salmonella
• 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;

o 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.