- IgA nephropathy is the most common cause of primary glomerulonephritis worldwide, typically presenting in young adults with a male predominance.
- Mesangial IgA deposition is seen in 3-16% of healthy individuals, suggesting there is a large, undiagnosed population with "latent" IgA nephropathy.
- On biopsy, IgA nephropathy shows mesangial proliferation and matrix expansion. Electron microscopy shows electron-dense deposits primarily in the mesangium.
- Clinically, 40-50% present with visible hematuria after upper respiratory infections. 30-40% have microscopic hematuria and mild proteinuria. Less than