Nephrotic Syndrome

Introduction

Nephrotic syndrome is a collection of symptoms and signs which form a clinical syndrome. It has a number of different causes, and is just one way that kidney disease can present, rather than a diagnosis itself. Nephrotic syndrome is characterised by a triad of heavy proteinuria, hypoalbuminaemia and oedema

Diagnostic criteria

  1. Proteinuria (>3g/24hr urine collection or protein: creatinine ratio >300mg/mmol)
  2. Hypoalbuminaemia (<25g/l)
  3. Oedema

Presentation

Symptoms

  • Periorbital oedema (low tissue resistance around the orbit)
  • Pitting peripheral oedema - arms or legs (reduced oncotic pressure of hypoalbuminaemia, RAAS activation, salt/water retention and effects on epithelial sodium channel)
  • Shortness of breath due to pulmonary edema or pleural effusion
  • Frothy urine due to proteinuria

Signs

  • Oedema
  • Ascites
  • Leukonychia

Laboratory investigations

  • 24 hour urine collection or urine protein:creatine ratio
  • U+E - renal function may be normal or reduced
  • LFT - hypoalbuminaemia
  • FBC - microcytic anaemia may be present
  • Cholesterol - raised

History taking

Once nephrotic syndrome has been found, questions should be asked to narrow down potential causes.

Recent/current acute or ongoing infections?

Drug history?

  • NSAIDS - Minimal change glomerulonephritis
  • Captopril, gold, penicillamine - Membranous nephropathy

Allergies?

Systemic review?

  • Vasculitis
  • Malignancy

Management

Investigation and history taking to find the cause. Symptomatic management:

  • Reduce salt intake
  • Diuretics - furosemide, spironalactone
  • ACEi/ARB (reduce cardiovascular risk, treat hypertension)

Differential diagnosis

Common
*Minimal change disease (most common, especially in children)
*Membranous nephropathy (2nd most common)
*Focal segmental glomerulosclerosis

Common, but present more often without nephrotic syndrome

Rare

  • Mesangiocapillary glomerulonephritis
  • Alport's syndrome (see inherited kidney disease)
  • Lupus nephritis

Many of these causes are covered under glomerulonephritis or other pages.

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