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.

Inclusion Criteria: Cohort A 1. ≥18 years of age at the time of recruitment 2. IgAN diagnosis confirmed with a renal biopsy 3. Episodic/Intermittent Loin Pain (defined as pain at least once every 6 months) 4. Have the capacity to consent to the study Cohort B 1\) ≥18 years of age at the time of recruitment 2) IgAN diagnosis confirmed with a renal biopsy 3) No history of loin pain 4) Have the capacity to consent to the study Exclusion Criteria: Cohort A 1. Constant loin pain 2. Infrequent loin pain (no pain experienced in the last 6 months) 3. Inability to differentiate loin pain from back pain 4. Other renal diseases 5. Therapies that interfere with immune-mediation like steroids and complement inhibitors 6. Kidney transplant recipients 7. Current participation in an interventional study that may affect kidney function 8. Patients on dialysis 9. Patients with implants that are not MRI-safe (pacemakers, implantable defibrillators, cochlear implants, some shunts, neurostimulators, some aneurysm clips, etc.) Cohort B 1. Other renal diseases 2. Therapies that interfere with immune-mediation like steroids and complement inhibitors 3. Kidney transplant recipients 4. Current participation in an interventional study that may affect kidney function 5. Patients on dialysis 6. Patients with conditions/implants that are not MRI-compatible (claustrophobia, pacemakers, implantable defibrillators, cochlear implants, some shunts, neurostimulators, some aneurysm clips, etc.)