Mediators of Loin Pain in IgA Nephropathy

The goal of this observational study is to learn about loin pain in people with Immunoglobulin A nephropathy (IgAN). The main question it aims to answer is: What changes occur in the kidneys, urine, and blood when people with IgAN experience loin pain? Participants will have MRI scans of their kidneys, provide urine and blood samples, and have their latest kidney function test results reviewed. For participants who experience loin pain, these assessments will be carried out during a pain episode and again when they are pain-free, so the results can be compared.