Anti-glomerular basement membrane nephritis following IgA vasculitis in a child: a diagnostic challenge.

Anti-glomerular basement membrane (anti-GBM) nephritis is a rare but highly aggressive cause of rapidly progressive glomerulonephritis (RPGN). Early recognition is essential, as delayed diagnosis leads to irreversible kidney damage and poor prognosis. We report an 8-year-old girl with anti-GBM nephritis initially misattributed to kidney involvement of IgA vasculitis (IgAV). Diagnosis was confirmed by markedly elevated anti-GBM antibodies and kidney biopsy findings. Despite plasma exchange and immunosuppressive therapy, kidney function deteriorated to kidney failure within several months. This case provides an important clinical insight for pediatric nephrologists: worsening urinary findings or kidney function during follow-up of IgAV should prompt consideration of RPGN and appropriate serological screening, as well as timely kidney biopsy, rather than being attributed solely to IgAV nephritis.