Glomerulonephritis (GN) and nephropathies
Definitions
- Glomerulonephritis (GN): Inflammatory diseases primarily affecting glomeruli.
- Nephropathies: General term for kidney diseases, may involve glomeruli, tubules, interstitium, or vasculature.
Classification
By clinical syndrome
By etiology
Etiology
Primary glomerular diseases
- IgA nephropathy (Berger disease).
- Membranous nephropathy.
- Minimal change disease.
- Focal segmental glomerulosclerosis.
- Membranoproliferative GN.
Secondary glomerular diseases
- Systemic lupus erythematosus (SLE).
- Diabetes mellitus.
- Amyloidosis.
- Post- streptococcal infections.
- Goodpasture syndrome.
Pathogenesis
Immune- mediated injury (most common)
- Deposition of circulating immune complexes (e.g., post-streptococcal GN).
- In situ immune complex formation (e.g., anti-GBM antibodies in Goodpasture).
- Complement activation → recruitment of inflammatory cells, release of proteases and oxidants → glomerular basement membrane (GBM) damage.
- Podocyte injury → proteinuria.
Non- immune mechanisms
- Metabolic injury (diabetic nephropathy → glycosylation of GBM proteins).
- Amyloid or light- chain deposits → structural disruption.
Clinical manifestations
Nephritic syndrome (typical in proliferative GN)
- Hematuria (cola or tea- colored urine).
- RBC casts in urine.
- Oliguria, azotemia.
- Hypertension.
- Mild to moderate proteinuria.
Nephrotic syndrome
- Massive proteinuria (>3.5 g/ day).
- Hypoalbuminemia → generalized edema (anasarca).
- Hyperlipidemia, lipiduria.
- Increased risk of thromboembolic events (loss of antithrombin III).
Rapidly progressive GN
- Rapid decline in GFR over days to weeks.
- Severe oliguria.
- Crescent formation on biopsy.
Chronic glomerulonephritis
- Progressive proteinuria and hematuria.
- Slowly progressive renal failure → end- stage renal disease (ESRD).
- Hypertension common.