Berger disease

IgA nephropathy is caused by deposition of poorly galactosylated IgA1-containing immune complexes in the glomerular mesangium, leading to mesangial cell proliferation and complement activation (mainly alternative pathway). This triggers an inflammatory response causing glomerular injury. Clinically, it presents most often in young males with episodes of gross hematuria concurrent with or shortly after mucosal infections (upper respiratory, GI), distinguishing it from post-streptococcal glomerulonephritis, which has a latency period of 1-3 weeks. Some patients present with asymptomatic microscopic hematuria and mild proteinuria discovered incidentally. Renal biopsy is the gold standard for diagnosis, showing mesangial proliferation on light microscopy, IgA-dominant deposits on immunofluorescence, and electron-dense deposits in the mesangium on electron microscopy. IgA nephropathy is associated with Henoch-Schönlein purpura (IgA vasculitis), which is considered a systemic form of the same underlying pathology, presenting with palpable purpura, arthralgia, abdominal pain, and renal involvement, typically in children. It's also associated with liver disease (cirrhosis) and celiac disease due to impaired hepatic clearance of IgA complexes. Prognosis is variable; roughly 30-40% of patients progress to end-stage renal disease over 20-25 years. Risk factors for progression include persistent proteinuria (>1g/day), hypertension, and renal insufficiency at presentation. Treatment includes ACE inhibitors/ARBs for proteinuria and blood pressure control, and immunosuppression (corticosteroids) in cases with significant proteinuria or declining renal function. Fish oil may be used as an adjunct. This is a high-yield topic for boards, often tested with vignettes distinguishing IgA nephropathy from post-streptococcal GN based on timing of hematuria relative to infection.