Mediators of Loin Pain in IgA Nephropathy

LO-PAIgN: Mediators of Loin Pain in Immunoglobulin-A 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.

Some people with Immunoglobulin A nephropathy (IgAN) experience loin pain, or pain around the kidneys, but the underlying cause of this pain is not well understood. Current treatment options often do not provide effective pain relief, and a better understanding of the mechanisms involved may support the development of more targeted treatments in the future and help understand what this pain may mean for the disease state.

This observational study will investigate whether loin pain in IgAN is associated with changes in the kidneys, kidney function, and biological markers in blood and urine. Participants will undergo magnetic resonance imaging (MRI) of the kidneys to assess whether there are structural or tissue-related differences during episodes of pain compared with pain-free periods. The study will also assess the renal pelvis, the urine-collecting part of the kidney, to explore whether it may be involved in the development of pain.

Blood and urine samples will be collected to investigate whether biological molecules differ during pain episodes and pain-free periods. Urine samples will also be examined under the microscope to assess for the presence of blood cells or other features that may suggest kidney injury or inflammation.

Participants' most recent kidney function test results will also be reviewed to explore whether kidney function is associated with the presence or severity of loin pain. Together, these assessments aim to provide a better understanding of what happens in the kidneys and biological samples of people with IgAN when they experience loin pain.

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.)