Nephrotic Syndrome Flashcards
What is nephrotic syndrome?
This is defined as the presence of proteinuria (>3.5g/24 hours), hypoalbuminaemia (<30g/L) and peripheral oedema.
Despite heavy proteinuria and lipiduria, the urine contains few cells or casts.
What are the causes of nephrotic syndrome?
Most common cause is minimal change disease.
Focal segmental glomerulosclerosis (FSGS)
Membranous nephropathy
Diabetic nephropathy
It can also develop in patients with IgA nephropathy, membranoproliferative glomerulonephritis and post-infectious glomerulonephritis
What is minimal change disease?
Usually occurs in kids less than 10 years old.
Minimal change refers to light microscopic findings that often reveal normal glomeruli or mild mesangial proliferation.
It is responsive to steroids.
What is FSGS?
FSGS is when there are segmental areas of mesangial collapse and sclerosis affecting some but not all glomeruli.
FSGS is either primary (idiopathic) or secondary to HIV, obesity and reflux nephropathy.
How does FSGS present?
FSGS often presents with haematuria, HTN and reduced renal function
How is FSGS treated?
Primary FSGS responds to immunosuppression
Secondary FSGS are treated with reducing intraglomerular pressure (renin-angiotensin blockade)
Patients are often resistant to steroids and renal biopsy is required to confirm diagnosis
What is membranous nephropathy?
Most common cause of nephrotic syndrome in adults.
Basement membrane thickening without associated cellular proliferation or inflitration
Although membranous nephropathy is usually idiopathic, many cases are secondary to hepatitis B, autoimmune disease, malignancy and adverse drug reactions (including gold, penicillamine and NSAIDs)
Histology of membranous nephropathy
Immunofluoresence reveals diffuse, granular IgG deposition throughout the capillary walls and electron microscopy shows electron dense deposits in the sub epithelial space.
What is diabetic neuropathy?
This is usually heralded by microalbuminuria, then a progressive fall in GFR.
There is a combination of pathogenic process such as glomerular hyper filtration, hyperglycaemia and glycation of matrix proteins.
What is amyloidosis?
Responsible for around 10% of nephrotic syndrome.
There are 2 ,major sub-types such as:
-AL primary amyloid, which is a light-chain dyscrasia where monoclonal light chains from amyloid fibrils.
-AA amyloid which is associated with chronic inflammatory disease
What is the pathophysiology of nephrotic syndrome?
Glomerular proteinuria develops when the components of the filtration barrier are disrupted by disease. The heavier the protein loss, the more likely the development of full blown syndrome and worsening of renal function.
The oedema is due to a combination of a decrease in oncotic pressure from the hypoalbuminaemia, as well as a primary renal sodium retention in the collecting tubule
Differential diagnosis of nephrotic syndrome
Minimal change disease FSGS Diabetic nephropathy Membranous nephropathy Amyloidosis IgA nephropathy Multiple myeloma Lupus nephritis Alport's syndrome
Major complications of nephrotic syndrome
Proteinuria and oedema Protein malnutrition Hypovolaemia due to over-diuresis AKI due to hypovolaemia , ischaemic injury Hyperlipidaemia Hypercoagulability causing thrombosis Immunocomprised state due to loss of immunoglobulins Rapidly progressive glomerulonephritis
Diagnostic approach of nephrotic syndrome
Careful hx and physical examination
Qualification of proteinuria either a 24 hour urine collection or ACR
Urinalysis with microscopy
Urine protein electrophoresis
Serological studies for autoimmune scree, serum free light chains, syphillis serology and hep. B and C serology
Renal biopsy
CI to renal biopsy
Bleeding diathesis resistant to correction
Multiple, bilateral renal cysts
Renal tumour
Hydronephrosis
Active renal infection
Small kidneys, secondary to chronic irreversible disease
severe resistant HTN
