Nephrotic Syndrome

Question 1

What is nephrotic syndrome a triad of?

Answer 1

• Proteinuria >3g/24hr
• Hypoalbuminaemia < 30g/L
• Oedema

Question 2

What are primary causes of nephrotic syndrome?

Answer 2

• Minimal change disease
• Membranous nephropathy
• Focal segmental glomerulosclerosis (FSGS)
• Membranoproliferative GN

Question 3

What are secondary causes of nephrotic syndrome?

Answer 3

• Diabetes mellitus
• Lupus nephritis
• Myeloma
• Amyloid
• Pre-eclampsia

Question 4

What is the spectrum of glomerular diseases?

Answer 4

Question 5

What is the pathophysiology of nephrotic syndrome?

Answer 5

• Filtration barrier of kidney is formed by podocytes, glomerular basement membrane (GBM) and endothelial cells
• Proteinuria results from podocyte pathology
• Abnormal fxn in minimal change disease
• Immune-mediated damage in membranous nephropathy
• Podocyte injury/death in FSGS

Question 6

What is the presentation of nephrotic syndrome?

Answer 6

• Generalised
• Pitting oedema
• Fatigue
• Foamy or bubbly urine

Question 7

What is minimal change disease?

Answer 7

• 75% cases in children and 25% in adults
• Idiopathic (most) or in associated w drugs (NSAIDs, lithium) or paraneoplastic (Hodgkin’s lymphoma)
• Does NOT cause renal failure

Question 8

How is minimal change disease diagnosed?

Answer 8

Light microscopy is normal (hence the name)

Question 9

What is the management of minimal change disease?

Answer 9

• Prednisolone 1mg/kg for 4-16 wks
• Cyclophosphamide next step for steroid resistant cases

Question 10

What is focal segmental glomerulosclerosis (FSGS)?

Answer 10

• Commonest glomerulonephritis seen on renal biopsy
• Primary (idiopathic) or secondary (HIV, heroin, lithium, lymphoma)
• All at risk of progressive CKD and kidney failure

Question 11

How is FSGS diagnosed?

Answer 11

Renal biopsy

• Shows focal + segmental sclerosis and hyalinosis on light microscopy
• Effacement of foot processes on electron microscopy

Question 12

What is the treatment for FSGS?

Answer 12

• ACE-i / ARB for BP control
• Corticosteroids in primary disease

Question 13

What is membranous nephropathy?

Answer 13

• Primary or secondary to malignancy, infection or immunological disease
• Indolent disease w/ spontaneous remission in 25%

Question 14

How is membranous nephropathy diagnosed and managed?

Answer 14

• Dx → anti-phospholipase A2 receptor antibody in 70-80% idiopathic disease
• ACE-i / ARB and BP control in all

Question 15

What are the 4 principles for management of nephrotic syndrome?

Answer 15

• Reduce oedema
• Treat underlying cause
• Reduce proteinuria
• Complications

Question 16

How do you reduce oedema in nephrotic syndrome?

Answer 16

• Fluid (1L/day) and salt restriction
• Diuresis with loop diuretics
• If gut oedema affects oral absorption of diuretics, give IV
• Aim 0.5-1kg weight loss per day to avoid intravascular volume depletion

Question 17

How do you treat the underlying cause?

Answer 17

• Adults need a renal biopsy (diuresis may be needed first if gut oedema)
• In children, minimal change disease is commonest; biopsy is not needed unless steroid resistant or clinical features of a different cause

Question 18

How do you reduce proteinuria?

Answer 18

• ACE-i / ARB reduces proteinuria
• May not be needed in minimal change disease

Question 19

What are possible complications of nephrotic syndrome?

Answer 19

• Thromboembolism → hypercoagulable due to inc clotting factors, reduced anti-thrombin III and platelet abnormalities; increased risk of VTE including DVT/PE, treat with heparin and warfarin
• Infection → urine losses of immunoglobulins leads to increased risk of urinary, respiratory and CNS infection; ensure pneumococcal vaccination given
• Hyperlipidaemia → inc cholesterol, LDL and triglycerides; thought due to hepatic synthesis in respons to decreased oncotic pressure and defective lipid breakdown