Overview

Minimal change disease (MCD) is the most common form of nephrotic syndrome in children. Its exact pathogenesis is unclear and immunofluorescence and light microscopy testing on biopsies showed no or minimal changes, hence MCD’s name. However, with electron microscopy, a diffuse loss of podocytes is seen, explaining proteinuria and the development of nephrotic syndrome.

Overview

Minimal change disease (MCD) is the most common form of nephrotic syndrome in children. Its exact pathogenesis is unclear and immunofluorescence and light microscopy testing on biopsies showed no or minimal changes, hence MCD’s name. However, with electron microscopy, a diffuse loss of podocytes is seen, explaining proteinuria and the development of nephrotic syndrome.

Epidemiology

  • MCD is the most common cause of nephrotic syndrome in children
  • MCD is most commonly seen in young children 1-8 years old

Risk Factors

  • Leukaemia – MCD is associated with leukaemia
  • Hodgkin’s lymphoma (HL) – MCD is associated with HL and may be the initial presenting symptom in some
  • Recent viral illness – a dysregulated immune system is thought to play a role in MCD

Presentation

  • Patients present with nephrotic syndrome:
    • Proteinuria (>3.5 g/24hr)
    • Hypoalbuminaemia
    • Oedema
  • Other features that may also be seen in nephrotic syndrome include:
    • Hyperlipidaemia
    • Hypercoagulability
    • Immunodeficiency
  • Patients are generally normotensive – hypertension is rare in MCD.

Investigations

  • Urinalysis:
    • Proteinuria is seen – generally intermediate-sized proteins (e.g. albumin or transferrin)
    • No significant haematuria is generally seen
  • Urine microscopy and culture:
  • 24-hour urinary protein or urine protein:creatinine ratio:
    • Shows proteinuria
  • Urea and electrolytes (U&Es) and estimated glomerular filtration rate (eGFR):
    • Urea and creatinine are generally normal, however, urea may be slightly elevated in some cases
    • EGFR is normal
  • Serum albumin:
    • Low (generally <30 g/L)
  • Serum lipids:
    • Shows hypertriglyceridaemia/hypercholesterolaemia
  • C3 and C4 complement levels:
  • Liver function tests (LFTs):
    • To rule out chronic liver disease as a cause of hypoalbuminaemia
  • Renal ultrasound:
    • To rule out structural abnormalities
  • Kidney biopsy:
    • Not commonly performed unless atypical features are present (e.g. <1 year old, hypertension, haematuria, renal dysfunction, poor response to corticosteroids)
    • MCD can be diagnosed without a biopsy provided no atypical features are present
    • Light microscopy and immunofluorescence are normal
    • Electron microscopy is diagnostic and shows a loss of podocytes

Management

Most cases are responsive to steroids, therefore oral corticosteroids are first-line. Other options include:

  • Cyclophosphamide or ciclosporin if corticosteroids are ineffective

Complications

  • Relapse of MCD:
    • May happen in 2/3 of patients
  • Infection:
    • Due to urinary loss of immunoglobulins or immunosuppressive treatment
  • Thrombosis:
    • Due to the loss of antithrombin III in the urine

Prognosis

MCD generally has a very good prognosis as around 80% of patients are steroid-responsive.

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