Paediatrics: Nephrotic syndrome

2021-03-04 12:00 AM

Heavy proteinuria (urinary protein to creatinine ratio >200mg/mmol).

Nephrotic syndrome

This is defined as a combination of:

  • Heavy proteinuria (urinary protein to creatinine ratio >200mg/mmol).
  • Hypoalbuminaemia (albumin <25g/L).
  • Oedema.
  • Hyperlipidaemia.

The incidence is approximately 2/100,000 children with a peak age of onset in children aged <6yrs. Boys are more commonly affected than girls (2:1) and there is an increased frequency in certain ethnic groups, e.g. Indian subcontinent. Nephrotic syndrome can be either primary or secondary

Primary

  • Congenital.
  • Infantile.

Secondary

  • Minimal change disease (MCD): commonest (85%).
  • Focal segmental glomerulosclerosis (FSGS; 10%).
  • Membranoproliferative glomerulonephritis (MPGN; 5%).
  • Membranous glomerulonephritis (MGN).

Classification

Nephrotic syndrome can be clinically classified as being either steroid-sensitive (SS), steroid-dependent or steroid-resistant (SR). The majority of MCD is SS.

  • MCD (SS), >95%.
  • FSGS (SS), 20%.
  • MPGN (SS), 55%.

Clinical features

Most children present with insidious onset of oedema, which is initially periorbital, but becoming generalized with pitting oedema. Periorbital oedema is often most noticeable in the morning on rising. Ascites and pleural effusions may subsequently develop.

Examination

This should establish the extent of dependent oedema, e.g. facial, ankle, scrotal, etc. Assessment should also include:

  • Height and weight (compare with previous/recent measurements).
  • BP.

Peripheral perfusion.

Investigations

Urine

  •  Urinalysis: protein +++.
  •  Microscopy: haematuria/casts (suggest causes other than MCD).
  • Na+If <10mmol/L suggests hypovolaemia. (Note: If the patient has received diuretics this is not accurate.)
  • Culture.
  • Protein: creatinine ratio (early morning urine specimen).

Bloods

  • Serum albumin (reduced, <25g/L).
  • U&E/creatinine (decreased sodium and total calcium—with normal ionized calcium).
  • C3/C4 (if decreased suggests not MCD).
  • Consider ANF, ASOT, ANCA, immunoglobulins if mixed nephritic/ nephrotic picture.
  • Lipids: total cholesterol/low-density lipoprotein (LDL)/very low-density lipoprotein (VLDL).
  • Haemoglobin may be increased or decreased depending on plasma volume.
  • Varicella-zoster immunity status.

Management

Patients should be admitted, particularly if this is their first episode or if there are concerns regarding complications. Management is initially aimed at fluid restriction and the prevention of hypovolaemia. A trial of oral steroid therapy to induce remission is also started. Prophylaxis against bacterial infection (particularly pneumococcal) is also required.

Treatment

  •  Treat hypovolaemia if present but albumin infusion is not routine.
  • Fluid restriction to 800–1000mL/24hr.
  • Diuretics if very oedematous and no evidence of hypovolaemia. Furosemide/spironolactone.
  • Steroid therapy:

o oral prednisolone 60mg/m2/day for 4wks;

o followed by 40mg/m2/alternate days for 4wks; then

stop—slow wean over next 4mths with a slow taper, but need to consider side-effects of steroids.

Other measures

  •  Diet (no added salt and healthy eating—not high protein).
  •  Prophylactic antibiotics (oral penicillin V) until oedema-free.
  •  Immunize with pneumococcal vaccine.