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  3. Idiopathic Nephrotic Syndrome in Children

Idiopathic Nephrotic Syndrome in Children

NHS Scotland GGC Clinical guidelines 201 Idiopathic Nephrotic Syndrome Management in Children. Last revised: Sep 2022.

Background Information

Idiopathic nephrotic syndrome is a clinical diagnosis describing nephrotic syndrome of unknown cause, before biopsy

Causes of idiopathic nephrotic syndrome:
  • Minimal change disease (>90%)
  • Focal segment glomerulosclerosis (FSGS)

 

Note that a renal biopsy is required to reveal the underlying cause of idiopathic nephrotic syndrome. However, this is not necessary if the patient responds to treatment.

  • Relapse is very common (occurs in the 1st year in up to 80-90% of patients) - can be triggered by URTI, allergies, vaccinations
  • Progression to CKDChronic kidney disease or ESRDEnd-stage renal disease is rare in presumed minimal change disease, especially when it is steroid-sensitive
  • Hypertension is uncommon or mild

Main complications:
 
Complication Underlying mechanism
Infection (leading cause of death) Urinary loss of immunoglobulins and complement factors
Hyperlipidaemia Low oncotic pressure → compensatory hepatic production of lipoproteins
Thromboembolism Urinary loss of anticoagulant proteins (e.g. anti-thrombin III, protein C&S) → hypercoagulability
Anaemia Urinary loss of transferrin
Vitamin D deficiency Urinary loss of vitamin D-binding protein
 

Diagnosis Guidelines

Triad of:
  • Heavy proteinuria (>3.5g / day)
  • Hypoalbuminaemia (<25 g/L)
  • Oedema (peri-orbital oedema, lower limb pitting oedema, ascites, scrotal / vulval oedema)

Other features:
  • 1-10 y/o
  • Normal BP (hypertension is atypical)
  • Hyperlipidaemia (due to hepatic compensation)
  • ↓ Vitamin D (from urinary loss)
  • Microscopic haematuria (macroscopic is atypical)
  • Normal creatinine

  • Height and weight
  • Oedema assessment
  • Fluid status assessment

Blood tests:
  • FBC, U&E, LFT, bone profile (including serum albumin)
  • Vitamin D
  • Varicella IgG

Urine testing:
  • Urinalysis
  • Urinary PCRProtein:creatinine ratio
  • Urine sodium concentration

 

Note that urinalysis (urine dipstick) should only be used to detect proteinuria but NOT to quantify proteinuria. To quantify proteinuria:

  • 24-hour urine collection is the gold standard but not practical, so it is rarely performed
  • Spot urine PCR is the preferred method

The following tests should only be performed in those with  atypical features to exclude alternative diagnoses:
 
Test Notes
ASOTAntistreptolysin O titer ↑ Suggests Streptococcal throat infection and possible PSGNPost-streptococcal glomerulonephritis
Anti-DNase ↑ Suggests Streptococcal throat infection and possible PSGNPost-streptococcal glomerulonephritis
C3/C4 ↓ C3 level may suggest:
  • C3 glomerulopathy (membranoproliferative glomerulonephritis)
  • PSGNPost-streptococcal glomerulonephritis
  • SLE
Hepatitis B serology Perform if high risk:
  • Family history of hepatitis B
  • History of travel in endemic areas

Management Guidelines

Offer the following to all patients:
  • Lifestyle advice (not necessary once in remission)
    • Fluid restriction (but not if the patient is hypovolaemic)
    • Low salt diet
 
  • High-dose oral prednisolone for 8-12 weeks + PPIProton pump inhibitor
    • Dose depends on body surface area
    • Click to view a typical regimen

Monitor BP and urine PCRProtein:creatinine ratio.

 

> 80-90% of children are steroid-responsive, therefore the current practice is to treat empirically first without renal biopsy. Renal biopsy should only be considered if refractory to steroid therapy.

Note that there is an increased risk of adrenal suppression after 4 weeks of high-dose steroids. See this article for more information on adrenal insufficiency.

Complication Management
↑ Infection risk Antibiotic prophylaxis is NOT routinely recommended
  • Only offer if severely oedematous / asitic
  • 1st line: phenoxymethylpenicillin (penicillin V)
  • 2nd line: erythromycin

Vaccinations
  • Pneumococcal vaccination - all children >2 y/o (repeat every 5 years)
  • Annual seasonal flu vaccination (NOT live nasal vaccination, but the non-live injection)
  • If varicella IgG -ve → VZV vaccine
Persistent oedema Diuretics:
  • 1st line: furosemide
  • 2nd line: add spironolactone / amiloride

20% albumin infusion
  • Note that there is a significant risk of fluid overload and pulmonary oedema
  • Only give in high dependency unit, after consultation with specialist
  • Furosemide should be given mid-infusion and at the end of the infusion
Vitamin D deficiency Measure 25-hydroxyvitamin D levels and treat any deficiency accordingly.

1st line: restart high-dose prednisolone
  • 60 mg/m2/day until in remission (-ve / trace only for protein for 3 consecutive days)
  • Then, weaning regimen

2nd line options (by specialist):
  • Levamisole
  • Cyclophosphamide
  • Calcineurin inhibitor (ciclosporin, tacrolimus)
  • Mycophenolate mofetil
  • Rituximab - last resort

References

Author: Adams Lau
Reviewer:
Last edited: 29/08/25