Definition:
Glomerulonephritis (GN) refers to a group of kidney diseases characterized by inflammation of the glomeruli, leading to varying degrees of hematuria, proteinuria, reduced glomerular filtration rate (GFR), hypertension, and edema.
It can present as acute, rapidly progressive, or chronic disease and may be primary (limited to kidneys) or secondary (as part of systemic illness).
Etiology:
Infectious causes:
- Group A beta-hemolytic streptococci (post-streptococcal GN)
- Bacterial endocarditis
- Hepatitis B, C
- HIV, syphilis
Autoimmune / Immune-mediated:
- Systemic lupus erythematosus (SLE)
- IgA nephropathy (Berger disease)
Others:
- Hereditary disorders (e.g., Alport syndrome)
Classification:
A. Based on Clinical Course:
- Acute glomerulonephritis (e.g., PSGN)
- Rapidly progressive glomerulonephritis (RPGN)
- Chronic glomerulonephritis
C. Based on Cause:
- Primary GN (renal-limited)
- Secondary GN (associated with systemic disease)
Pathogenesis:
- Immune-mediated injury is the primary mechanism.
- Antibodies or immune complexes deposit in the glomeruli.
- This triggers complement activation and inflammation.
- Leads to damage of the filtration barrier → hematuria, proteinuria, decreased GFR.
- In some types (e.g., RPGN), aggressive injury leads to crescent formation and rapid loss of renal function.