IgA nephropathy Flashcards
What is the pathophysiology of IgA nephropathy?
IgA nephropathy (Berger disease) is caused by mesangial deposition of abnormally glycosylated IgA in response to a mucosal infection. This leads to immune complex formation, mesangial cell proliferation, and glomerular injury.
What is the classic presentation of IgA nephropathy on USMLE?
Recurrent episodes of gross hematuria within days of an upper respiratory infection, normal complement levels, and RBC casts on urinalysis.
What are the characteristic clinical features of IgA nephropathy?
1) Gross hematuria following an upper respiratory infection (URI) (within days, not weeks like post-streptococcal GN).
2) Recurrent episodes of hematuria, often with flank pain and low-grade fever.
3) Asymptomatic microscopic hematuria in some cases.
4) Hypertension may develop over time, increasing risk of progression to ESRD.
How does IgA nephropathy differ from post-streptococcal glomerulonephritis (PSGN)?
- IgA Nephropathy: Hematuria occurs within days of a respiratory infection, normal complement levels.
- PSGN: Hematuria occurs weeks after infection, low complement (C3) due to immune complex deposition.
What laboratory findings are seen in IgA nephropathy?
1) Urinalysis: Proteinuria, hematuria, and RBC casts.
2) Serum complement levels are normal (unlike postinfectious GN).
3) Serum creatinine may be elevated if disease progresses.
4) Kidney biopsy (if needed): Mesangial IgA deposition on immunofluorescence.
When is a kidney biopsy indicated in IgA nephropathy?
A biopsy is indicated if there is rapid progression, nephrotic-range proteinuria (>3.5 g/day), or unclear diagnosis. Otherwise, diagnosis is often made clinically.
What are the risk factors for progression to end-stage renal disease (ESRD) in IgA nephropathy?
1) Hypertension (>140/90 mmHg at diagnosis).
2) Elevated serum creatinine.
3) Persistent proteinuria (>1 g/day for >6 months).
4) Slowly progressive course (>10 years).
Which factor is most indicative of poor prognosis in IgA nephropathy?
Hypertension at diagnosis is the strongest predictor of progression to chronic kidney disease and ESRD.
What is the treatment for IgA nephropathy?
1) ACE inhibitors or ARBs (to reduce proteinuria and slow progression).
2) Corticosteroids for severe proteinuria (>1 g/day despite ACEI/ARB therapy).
3) Supportive management (BP control, lifestyle modifications).
4) Kidney transplant if ESRD develops.
What role do corticosteroids play in IgA nephropathy?
Corticosteroids are used in severe cases with persistent proteinuria (>1 g/day despite ACE inhibitors/ARBs). They help reduce inflammation and slow disease progression.
What histologic finding is characteristic of IgA nephropathy on kidney biopsy?
Mesangial IgA deposition on immunofluorescence.
