IgA Nephropathy (Berger Disease)
Content of This Page
1- Definition & Types
2- Causes (Aetiology)
3- Pathophysiology
4- Clinical Features & Examination
5- Investigations
6- Management
7- Complications
8- Core Concepts
Definition & Types
IgA nephropathy (Berger disease) is a glomerular disease caused by deposition of IgA-containing immune complexes in the glomerular mesangium, leading to inflammation and potential progressive renal damage.
Types (based on presentation):
Episodic visible haematuria: Often following respiratory infections (“synpharyngitic”).
Asymptomatic microscopic haematuria: Found incidentally.
Nephritic presentation: Haematuria with proteinuria and hypertension.
Rapidly progressive glomerulonephritis (RPGN): Rare but severe, with crescent formation.
Causes (Aetiology)
The exact cause is unknown, but multi-hit pathogenesis is proposed:
Genetic predisposition: Common in Asians and Caucasians; familial clustering reported.
Environmental triggers:
Respiratory or gastrointestinal infections (mucosal antigens stimulate IgA production).
Possibly dietary antigens.
Underlying mechanism: Aberrant IgA1 molecules → immune complex formation → mesangial deposition.
Pathophysiology
Step 1: Overproduction of abnormally glycosylated IgA1 in response to mucosal antigen exposure.
Step 2: Formation of anti-glycan autoantibodies → immune complexes.
Step 3: Deposition in glomerular mesangium → mesangial proliferation, cytokine release.
Step 4: Leads to glomerular injury, proteinuria, haematuria, and fibrosis over time.
Clinical Features & Examination
| Feature | Description |
|---|---|
| Visible haematuria | Often after URTI or GI infection (within 1–2 days) |
| Microscopic haematuria | Common incidental finding |
| Proteinuria | Mild to moderate; nephrotic-range is rare |
| Hypertension | May develop as disease progresses |
| Renal impairment | Gradual decline in GFR in progressive cases |
Examination Tips:
BP measurement (hypertension common in advanced cases)
Oedema if proteinuria is significant
Look for signs of systemic disease if differential includes vasculitis
Investigations
| Test | Purpose | Findings |
|---|---|---|
| Urinalysis | Screen for blood/protein | Microscopic or visible haematuria; proteinuria |
| Urine microscopy | Confirms glomerular origin | Dysmorphic RBCs, RBC casts |
| Blood tests | Renal function, IgA | Elevated serum IgA in ~50%, assess eGFR/creatinine |
| Renal biopsy | Diagnostic gold standard | Mesangial proliferation and IgA deposits on immunofluorescence (Davidson 24e, Chap 18, p. 572) |
Management
General principles:
Based on risk of progression (proteinuria, hypertension, GFR decline)
-Low risk:
Normal BP, GFR, proteinuria <0.5–1 g/day
→ Observation and regular monitoring
-Intermediate risk:
Proteinuria >1 g/day or declining GFR
→ ACE inhibitors/ARBs to reduce proteinuria and protect kidneys
-High risk / Rapid progression:
Persistent proteinuria >1 g/day + impaired GFR
→ May consider immunosuppression (e.g. corticosteroids) after biopsy confirmation
Other Measures:
BP control: target <130/80 mmHg
Lifestyle: salt restriction, weight and glycaemic control if diabetic
Complications
Progressive chronic kidney disease (CKD) → may lead to end-stage renal disease (ESRD)
Nephrotic-range proteinuria
Hypertension
Rapidly progressive GN (rare)
Relapses, especially during infections
Core Concepts
Most common primary glomerulonephritis worldwide
Think IgA nephropathy in young males with visible haematuria during URTIs
Synpharyngitic haematuria = 1–2 days after infection (vs. post-streptococcal GN which is delayed)
Renal biopsy is needed for diagnosis and prognosis
Proteinuria is the strongest predictor of progression
No role for routine immunosuppression—only in selected high-risk cases