REN and kidney disorder: The Guide to Prognosis of Kidney Disease Improving Global Outcome (KDIGO) suggests that renin-angiotensin system inhibitors are used for patients with IgAN consisting of persistent proteinuria ≥0.5 g/d, and renin-angiotensin system inhibitors plus corticosteroid treatment are used for IgAN patients with proteinuria ≥1 g/d (2012).