Mediators of Loin Pain in IgA Nephropathy (LO-PAIgN)

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.

Study Overview

• Status: Not yet recruiting
• Conditions: IgA Nephropathy (IgAN)

Detailed Description

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.

• Study Type: Observational
• Enrollment (Estimated): 40

Contacts and Locations

• Study Contact: Name: Postgraduate Researcher; Phone Number: +447539398535; Email: ik186@leicester.ac.uk
• Study Contact Backup: Name: Chief Investigator; Email: hs328@leicester.ac.uk

Study Locations

• United Kingdom
  • Leicester
    • Leicester, Leicester, United Kingdom, LE1 7HA
      • University Hospitals of Leicester
      • Contact: Ishika Khan; Phone Number: 07539398535; Email: ik186@leicester.ac.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population will include adults aged 18 years or over with a renal biopsy-confirmed diagnosis of Immunoglobulin A nephropathy (IgAN) who have capacity to provide informed consent.

Participants will be recruited into two cohorts. Cohort A will include participants with IgAN who experience episodic or intermittent loin pain, defined as pain occurring at least once every 6 months. Cohort B will include participants with IgAN who have no history of loin pain.

Participants will be excluded if they have another renal disease, are receiving therapies that may affect immune-mediated pathways, have received a kidney transplant, are receiving dialysis, are taking part in an interventional study that may affect kidney function, or have conditions or implants that are not compatible with MRI scanning.

Description

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.)

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Cohort A: Loin pain group; This group would consist of patients with IgAN who experience loin pain episodes
Cohort B: No loin pain group; This group would consist of patients with IgAN who have never experienced loin pain

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in MRI-derived total kidney volume between active pain and follow-up assessments in participants with episodic loin pain	Differences in total kidney volume (mL)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit.
Change in MRI-derived renal cortical volume between active pain and follow-up assessments in participants with episodic loin pain	Differences in renal cortical volume (mL)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit.
Change in MRI-derived renal medullary volume between active pain and follow-up assessments in participants with episodic loin pain	Differences in renal medullary volume (mL)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit.
Change in MRI-derived renal T1 relaxation time between active pain and follow-up assessments in participants with episodic loin pain	Difference in renal T1 relaxation time (ms)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit.
Presence of renal pelvis abnormality on renal MRI in participants with episodic loin pain and participants with no history of loin pain	Presence of renal pelvis abnormality, including renal pelvis dilatation	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit.
Difference in MRI-derived total kidney volume between participants with episodic loin pain and participants with no history of loin pain	Difference in total kidney volume (mL)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Difference in MRI-derived renal cortical volume between participants with episodic loin pain and participants with no history of loin pain	Difference in renal cortical volume (mL)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Difference in MRI-derived renal medullary volume between participants with episodic loin pain and participants with no history of loin pain	Difference in renal medullary volume (mL)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Difference in MRI-derived renal T1 relaxation time between participants with episodic loin pain and participants with no history of loin pain	Difference in T1 relaxation time (ms)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Assessment of organ-level changes between pain-prone patients and those with no history of loin pain using structural renal magnetic resonance imaging (MRI)	Presence of renal pelvis abnormality, including renal pelvis dilatation	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Untargeted Liquid Chromatography-Tandem Mass spectrometry (LC-MS/MS) analysis to analyse differences in the urinary proteome between an active pain episode and when it subsides	Differences in abundance ratios	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit
Untargeted Liquid Chromatography-Tandem Mass spectrometry (LC-MS/MS) analysis to analyse the differences in the urinary proteome between pain-prone patients and those with no history of loin pain	Differences in abundance ratios	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Assessing the difference in molecules of interest between an active pain episode and when it subsides using enzyme-linked immunosorbent assay (ELISA) in urine, serum, and plasma	Differences in concentrations (w/v)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit
Assessing the difference in molecules of interest between pain-prone patients and those who do not have a history of loin pain using enzyme-linked immunosorbent assay (ELISA) in urine, serum, and plasma.	Differences in concentrations (w/v)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Comparing the presence of urinary factors that indicate active intra-renal injury between an active pain episode and when it subsides using urine microscopy	Difference in abundance (count per high magnification field)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit
Comparing the presence of urinary factors that indicate active intra-renal injury between an pain-prone patients and those with no history of loin pain using urine microscopy	Difference in abundance (count per high magnification field)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.
Comparing the presence of urinary factors that indicate active intra-renal injury between an active pain episode and when it subsides using the urine dipstick test	Difference in presence (Yes/No)	Within 72 hours of active loin pain onset and at follow-up assessment at least 2 weeks after the first visit
Comparing the presence of urinary factors that indicate active intra-renal injury between an pain-prone patients and those with no history of loin pain using the urine dipstick test	Difference in presence (Yes/No)	Within 72 hours of pain onset for participants with episodic loin pain and baseline assessment after enrolment for participants with no history of loin pain.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in estimated glomerular filtration rate between participants with episodic loin pain and participants with no history of loin pain	Difference in estimated glomerular filtration rate (mL/min/1.73 m²)	Within the 12 months before or at enrolment

Collaborators and Investigators

• Sponsor: University of Leicester
• Collaborators: University Hospitals, Leicester
• Investigators: Principal Investigator: Haresh Selvaskandan, MBChB, MRCP, MRes, PhD, University of Leicester, University Hospitals of Leicester

Study record dates

Study Major Dates

• Study Start (Estimated): August 20, 2026
• Primary Completion (Estimated): December 20, 2027
• Study Completion (Estimated): June 2, 2028

Study Registration Dates

• First Submitted: June 2, 2026
• First Submitted That Met QC Criteria: June 9, 2026
• First Posted (Actual): June 16, 2026

Study Record Updates

• Last Update Posted (Actual): June 16, 2026
• Last Update Submitted That Met QC Criteria: June 9, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: IgA nephropathy; IgAN; Renal pain; Kidney pain; Flank pain; Loin pain
• Additional Relevant MeSH Terms: Urogenital Diseases; Pain; Neurologic Manifestations; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Autoimmune Diseases; Immune System Diseases; Glomerulonephritis; Nephritis; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Glomerulonephritis, IGA; Flank Pain
• Other Study ID Numbers: 1104; 364280 (Other Identifier: Health Research Authority)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The nature of the study warrants within-group and between group comparisons. Individual data will not be valuable in a meaningful way as it is an observational case-control study.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No