Nephritic syndrome is a common cause of acute kidney injury and is seen in a variety of underlying diseases such as glomerulonephritis, lupus nephritis, and IgA nephropathy. It can lead to rapid decline in kidney function, and early recognition and treatment are crucial to prevent permanent kidney damage and progression to chronic kidney disease.
Therefore, understanding the pathogenesis of nephritic syndrome is important in order to understand the underlying mechanisms of kidney injury and develop appropriate treatments.
M.C cause of nephritic syndrome in pediatric age group. It occurs 14 days after skin or throat infection. It is characterized by antigen-antibody complex formation (type 3 hypersensitivity reaction). Clinical features: Cola coloured urine, sore throat 14 days prior to this
All the glomeruli are affected. Presence of increased cellularity of glomerulus (diffuse hypercellularity)
Electron microscopic examination
Presence immune complexes (Type III hyper sensitivity). Immune complexes are deposited in sub-epithelial areas known as subepithelial hump
There is increased proliferation of parietal epithelial cells and infiltration of monocytes, neutrophils and deposition of fibrin in glomeruli (Responsible for formation of crescent)
Rapid proliferation results in decline in kidney function in a short duration of time.
It is of following 3 types
Anti GBM antibody disease/ Goodpasture syndrome.
Immune complex disease e.g. SLE
Pauci-immune disease – It is associated with vasculitis disorder like Wegener’s glomerulonephritis
More the number of the crescents in glomeruli, more is the severity of disease.
It is seen in
Immune complex forming disorders like leukemia and lymphoma.
Berger Disease / IgA Nephropathy
Most common cause of glomerulonephritis in adults. It occurs 2-3 days after sore-throat / upper respiratory tract infection. Abnormal IgA antibodies are deposited in mesangial cells. Mesangial cells have CD71 receptors
Biopsy finding with immunofluorescence:
Shiny yellow green appearance of material
Confirm immune complexes in mesangium
There is a defect in a 5 chain of collagen type IV (note: a 4 chain of college is defective in familial hematuria).
Presence of abnormal thickening, there will be variations in the thickness of basement membrane (at some places basement membrane is thick and other places it is thin) causing splitting of lamination in basement membrane, this kind of variation in thickness is called “basket weave appearance”. This is seen in electron microscopy.
Alport syndrome can have AD, AR, X linked dominant (most common) and X linked recessive inheritance
Granular Vs. Linear immunofluorescence
Associated with immune complex deposition in linear fashion.
Scattered deposition of immune complexes along glomerular basement membrane.
Most common cause of nephrotic syndrome in children, especially 2-6 years of age.
Generalized Edema (it occurs due to excessive salt and water and hypoalbuminemia). Massive Proteinuria occurs resulting in frothiness of urine. It is characterized by selective proteinuria. Therefore, patients have a very good response to steroids. Under light microscopy no abnormality is detected.
In normal biopsy there are podocytes (foot process) seen. But Biopsy of MCD - presence of effacement / + flattening of podocytes, only picked by electron microscopy
It is the most common cause of nephrotic syndrome in elderly patients.
Idiopathic(In idiopathic variant , antibodies are formed against phospholipase A2 receptor)
Connective tissue disorders
This condition is characterized by Subepithelial immune complex deposition. On electron microscope: it appears as black electron dense deposits in the subepithelial region giving SPIKE and DOME appearance. On immunofluorescence: granular deposits are seen.
Membranous glomerulopathy is an important cause of Non-selective proteinuria. So steroids alone are not sufficient in these patients. along with steroids cyclosporine is also given. Animals model: HEYMANN NEPHRITIS model. Rat kidney antigen used is Megalin
Focal Segmental Glomerulosclerosis
It is the most common cause of nephrotic syndrome in adults. It is associated with HIV infection, single kidney and sickle cell anemia. Worst prognosis: collapsing variant as it is associated with HIV. Best prognosis: glomerular Tip type
MPGN Type I
MPGN- membranoproliferative glomerulonephritis is also called Measangio-capillary glomerulonephritis. Characterized by thickening of basement membrane and subendothelial deposits. Basement membrane material covers Subendothelial Deposit on both sides. This is responsible for “Tram-Track appearance of basement membrane “
MPGN Type II
Due to deposition of amorphous electron dense material in basement membrane k/as dense deposit disease. Specific antibody: C3 nephritic factor
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