Immunoglobulin A (IgA) nephropathy develops secondary to mesangial deposition of IgA and is a common primary cause of glomerulonephritis. Peak age of presentation is in the second and third decade, although patients may present at any age. The disease is more common in males than in females, with the greatest frequency in individuals of Northern European or Asian descent. There is also an increased risk of IgA nephropathy in patients with celiac disease.

Patients may present in any of the following ways:

• Recurrent hematuria following viral pharyngeal or gastrointestinal tract infections
• Asymptomatic detection of hematuria and proteinuria on routine screening
• Rapidly progressive disease with associated edema, hypertension, hematuria, and renal insufficiency

In children, it may present with IgA vasculitis (formerly Henoch-Schönlein purpura) after a viral infection.