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
- Proteinuria (>3g/24hr urine collection or protein: creatinine ratio >300mg/mmol)
- Hypoalbuminaemia (<25g/l)
- 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
- Diabetic Nephropathy
- Amyloidosis (most often AL type from multiple myeloma)
- IgA nephropathy
Rare
- Mesangiocapillary glomerulonephritis
- Alport's syndrome (see inherited kidney disease)
- Lupus nephritis
Many of these causes are covered under glomerulonephritis or other pages.