Nephritic Syndrome

•    Definition: Inflammatory glomerular disease characterised by:

o    Haematuria (often macroscopic)

o    Proteinuria (<3.5 g/day)

o    Hypertension

o    Oliguria ± AKI

o    Red cell casts in urine

•    Common Causes:

o    IgA nephropathy

o    Post-streptococcal glomerulonephritis

o    Rapidly progressive glomerulonephritis (RPGN)

Nephrotic Syndrome

•    Definition: Non-inflammatory glomerular disease with:

o    Proteinuria >3.5 g/day

o    Oedema

o    Hypoalbuminaemia

o    Hyperlipidaemia

o    Increased risk of thrombosis (especially renal vein) and infection (loss of immunoglobulins)

•    Common Causes:

o    Children: Minimal change disease (MCD) – excellent steroid response

o    Adults:

    Membranous nephropathy

    Focal segmental glomerulosclerosis (FSGS)

    Diabetic nephropathy

    Amyloidosis

Key Glomerular Disorders

•    IgA Nephropathy (Berger’s Disease):

o    Most common primary glomerulonephritis worldwide

o    Macroscopic haematuria post-URTI

o    Mesangial proliferation + IgA deposition

o    Normal or mildly ↓ complement levels

o    May progress to CKD; ACEi for proteinuria, steroids in select cases

•    Post-Streptococcal Glomerulonephritis (PSGN):

o    Typically in children/young adults ~2 weeks after streptococcal pharyngitis/impetigo

o    Features: haematuria (cola-coloured urine), oedema, HTN

o    Investigations: ↓ C3, ↑ anti-streptolysin O (ASO)

o    Self-limiting; supportive treatment

•    Rapidly Progressive Glomerulonephritis (RPGN):

o    Medical emergency with rapid loss of renal function

o    Histology: crescent formation

o    Causes:

    Goodpasture’s syndrome: anti-GBM antibodies → GN + pulmonary haemorrhage

    ANCA-associated vasculitis:

    GPA (Wegener’s): c-ANCA (PR3), ENT/lung/kidney

    MPA: p-ANCA (MPO), lung + kidney

o    Treatment: high-dose steroids + cyclophosphamide ± plasmapheresis

•    Focal Segmental Glomerulosclerosis (FSGS):

o    Segmental sclerosis in parts of glomeruli

o    Common cause of nephrotic syndrome in Black adults

o    Secondary causes: HIV, heroin, obesity, sickle cell

o    Often steroid-resistant; may progress to ESRD

•    Minimal Change Disease (MCD):

o    Commonest nephrotic syndrome in children

o    Normal light microscopy; effacement of foot processes on EM

o    Excellent response to steroids

o    Relapse common; may be triggered by infections/allergens

•    Membranous Nephropathy:

o    Common cause of nephrotic syndrome in Caucasian adults

o    Pathology: subepithelial immune complex deposits

o    Associated with:

    Primary: anti-PLA2R antibodies

    Secondary: malignancy, HBV, SLE, NSAIDs

o    High risk of renal vein thrombosis

•    Membranoproliferative Glomerulonephritis (MPGN):

o    Tram-track appearance on LM (due to mesangial and basement membrane proliferation)

o    Associated with hepatitis C, cryoglobulinaemia, complement dysregulation

o    Low C3 due to persistent activation of complement

•    Alport Syndrome:

o    X-linked defect in type IV collagen

o    Features: haematuria, sensorineural deafness, anterior lenticonus

o    Family history often positive

•    Thin Basement Membrane Nephropathy:

o    Benign familial haematuria

o    Good prognosis; normal renal function