A 25-year-old Asian American man arrives at the emergency department in a panic. Except for a bout with bronchitis a week earlier, he has been healthy his entire life; today he has blood in his urine. What is the most likely cause of his hematuria and how should it be treated? (Points : 0.4) His Goodpasture syndrome should be treated with plasmapheresis and immunosuppressive therapy. His membranous glomerulonephritis should be treated with corticosteroids. His immunoglobulin A (IgA) nephropathy has no known effective treatments. His Kimmelstiel-Wilson syndrome should be treated with control of high blood pressure and smoking cessation.