✅ Model Answer:
• Diagnosis: IgA nephropathy (Berger disease) – most common primary glomerulonephritis worldwide.
• Evidence: Elevated Serum IgA , Synpharyngitic hematuria (1-2 days post-URI), normal C3 and C4, elevated serum IgA, normal BP and renal function, no RBC casts.
• Next step: Monitor BP, proteinuria, creatinine. Renal biopsy if persistent proteinuria (>0.5 g/day), hypertension, or declining renal function. ACE inhibitor/ARB if proteinuria.

✅ Model Answer:
• Pathogenesis: Aberrant glycosylation of IgA1 molecules → formation of immune complexes (IgA1 + anti-glycan antibodies) → deposition in the glomerular mesangium.
• Trigger: Often follows mucosal infections (URI, GI) – "synpharyngitic" hematuria (1-2 days after infection).
• Histology: Mesangial proliferation with IgA deposits (immunofluorescence).
• Complement: Normal C3 and C4 (unlike APSGN).
• Prognostic factors: Proteinuria, hypertension, crescents on biopsy, renal function decline.

✅ Model Answer:
• Synpharyngitic hematuria: Gross hematuria occurs 1-2 days after URI (classic presentation).
• Microscopic hematuria: Persistent between episodes.
• Proteinuria: Usually mild to moderate; nephrotic-range proteinuria occurs in <10%.
• Hypertension: May develop later (indicative of progression).
• Renal function: Usually normal at presentation; progressive decline in 30-40% over 20 years.
• Other triggers: GI infections, exercise, or stress.
• Age: Most common in adolescents and young adults.

✅ Model Answer:
• Urinalysis: Gross or microscopic hematuria, variable proteinuria, no RBC casts (unlike APSGN).
• Serum studies:
- C3, C4: Normal (key differentiator).
- Serum IgA: Elevated in 50% of cases.
- Creatinine, BUN: To assess renal function.
- ASO titer: Normal (differentiates from APSGN).
• Renal biopsy: Gold standard – shows mesangial IgA deposits on immunofluorescence. Indicated if persistent proteinuria >0.5 g/day, hypertension, or declining renal function.
• Skin biopsy: Not useful (unlike IgA vasculitis).
• Family history: Some familial forms exist.

✅ Model Answer:
• Mild disease (no proteinuria, normal BP): Observation, supportive care, monitor annually.
• Moderate disease (proteinuria >0.5 g/day):
- ACE inhibitor/ARB: First-line (reduces proteinuria and delays progression).
- Blood pressure control: Target <130/80 mm Hg (or <120/75 in children).
- Omega-3 fatty acids: May help reduce proteinuria (limited evidence).
• Severe disease (nephrotic-range proteinuria, crescents, declining GFR):
- Corticosteroids: Prednisone (for 4-6 months) – if crescents on biopsy.
- Immunosuppressants: Cyclophosphamide, mycophenolate mofetil (in refractory cases).
- Tonsillectomy: Controversial; may reduce episodes of gross hematuria (not recommended routinely).
• Supportive: Avoid NSAIDs, maintain good hydration, treat infections promptly.

✅ Model Answer:
• Chronic kidney disease (CKD): 30-40% of patients progress to ESKD over 20 years.
• Hypertension: Often develops as renal function declines.
• Nephrotic syndrome: In <10% of cases.
• Rapidly progressive glomerulonephritis (RPGN): Rare but severe – requires pulse steroids and cyclophosphamide.
• End-stage kidney disease (ESKD): Requires dialysis/transplantation (can recur in transplant).
• Recurrence: IgA nephropathy can recur in renal allograft (30-50%).
• Risk factors for progression: Persistent proteinuria (>1 g/day), hypertension, male sex, African-American ethnicity, crescents on biopsy.

✅ Model Answer:
• Prognosis:
- Variable: 30-40% develop ESKD within 20 years.
- Better prognosis: Children with isolated hematuria, normal BP, normal renal function.
- Poor prognosis: Persistent proteinuria >1 g/day, hypertension, crescents on biopsy, male sex.
- Spontaneous remission: Can occur in some cases.
• Long-term follow-up:
- Monitor BP: Annually.
- Monitor proteinuria: Spot urine protein/creatinine ratio annually.
- Monitor creatinine/eGFR: Annually.
- Manage hypertension: ACE inhibitor/ARB if proteinuria develops.
- Avoid NSAIDs: To prevent acute kidney injury.
- Treat infections promptly.

✅ Model Answer:
• IgA nephropathy:
- Isolated renal disease: No extrarenal manifestations.
- Presentation: Synpharyngitic hematuria (recurrent).
- Biopsy: Mesangial IgA deposits.
- Systemic symptoms: None.
- Treatment: ACE inhibitors, corticosteroids for severe disease.
- Prognosis: 30-40% progress to ESKD.
• IgA vasculitis (Henoch-Schönlein purpura):
- Systemic disease: Palpable purpura (classic), arthritis, abdominal pain, GI bleeding.
- Renal involvement: Can be identical to IgA nephropathy (both have mesangial IgA deposits).
- Presentation: Usually younger children (4-6 years).
- Biopsy: Mesangial IgA deposits + leukocytoclastic vasculitis in skin.
- Treatment: Supportive; corticosteroids for severe renal involvement or GI symptoms.
- Prognosis: Renal prognosis similar to IgA nephropathy; systemic symptoms usually resolve.