Condition Deep-Dives 11 min read·Updated 22 July 2026 Clinician-reviewed

IgG4-Related Kidney Disease

A UK Consultant Nephrologist on IgG4-related kidney disease — the renal face of IgG4-related systemic disease. Easily mistaken for malignancy or vasculitis, it is steroid-responsive and frequently transforms outcomes when recognised early.

  • Clinically Reviewed
  • NHS & NICE Aligned
  • UK Evidence-Based
  • Last Reviewed 22 July 2026

Professor Mohammed Mahdi Althaf

Consultant Nephrologist & Acute Physician

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Professor Mohammed Mahdi Althaf

MD, MSc, PgDip (Clin Ed), FRCP, FHEA, FASN

Consultant Nephrologist & Acute Physician · GMC 7216325

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Direct answer

IgG4-RKD: tubulointerstitial nephritis (commonest) or membranous-like GN. Suspect when there are mass-like renal lesions, multi-organ disease (pancreas, salivary glands, orbits), high IgG4, low complement. Steroids are first-line; rituximab for relapse. Most patients respond but relapse is common.

Key recommendation: Most common renal lesion: tubulointerstitial nephritis.

Quick answer

✓ Best choices

  • Vegetables, lower-potassium fruit and whole grains
  • Sensible portions of fish, eggs, chicken or tofu
  • Olive oil and unsalted nuts in small amounts

✓ Foods to limit

  • Added salt and ultra-processed foods
  • Phosphate additives in processed meats and ready meals
  • Sugary and energy drinks

Key takeaway

IgG4-RKD: tubulointerstitial nephritis (commonest) or membranous-like GN. Suspect when there are mass-like renal lesions, multi-organ disease (pancreas, salivary glands, orbits), high IgG4, low complement. Steroids are first-line; rituximab for relapse. Most patients respond but relapse is common.

Who should be cautious

People on dialysis, post-transplant, pregnant or breastfeeding, or taking prescription medication — confirm with your renal team before changes.

IgG4-Related Kidney Disease

Clinical presentation

Epidemiology

  • M:F ~ 3:1; median age 60–70
  • ~ 15% of IgG4-RD patients have kidney involvement
  • Often discovered incidentally on imaging done for other organ disease (pancreas, salivary glands)

Renal Presentations

  • Asymptomatic raised creatinine
  • Mild–moderate proteinuria (< 3 g if TIN; nephrotic if membranous-like GN)
  • Mass-like or wedge-shaped low-attenuation cortical lesions on CT (may be misdiagnosed as malignancy or lymphoma)
  • Diffuse renal swelling
  • Hydronephrosis from retroperitoneal fibrosis or ureteric encasement

EXTRA-RENAL FEATURES (key clues):

  • Autoimmune pancreatitis type 1 — diffuse pancreatic enlargement, painless jaundice
  • Sialadenitis (Mikulicz syndrome — bilateral submandibular and parotid swelling)
  • Dacryoadenitis, orbital pseudotumour
  • Retroperitoneal fibrosis (chronic periaortitis)
  • Aortitis / periaortitis — risk of aneurysm
  • Riedel's thyroiditis
  • Sclerosing cholangitis
  • Lymphadenopathy

Diagnosis

Bloods

  • Serum IgG4 elevated (> 1.35 g/L) in 70–90% — but raised IgG4 is non-specific and a normal value does not exclude IgG4-RD
  • Total IgG raised
  • Eosinophilia common
  • Hypocomplementaemia (low C3 / C4) — more often than non-renal IgG4-RD
  • ESR / CRP modestly raised
  • ACR variable
  • ANCA, ANA, dsDNA negative (helps exclude vasculitis / lupus)

Imaging

  • CT/MRI: round or wedge-shaped hypoattenuating cortical lesions; diffuse swelling; pelvic / peripelvic infiltration
  • PET-CT useful to map multi-organ disease activity
  • MRA / aorta imaging if peri-aortic disease suspected

BIOPSY (gold standard):

  • Kidney biopsy or biopsy of another involved organ
  • Lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells (> 10 IgG4+ plasma cells/HPF; IgG4:IgG ratio > 40%)
  • Storiform (whorled, mat-like) fibrosis
  • Obliterative phlebitis
  • Tubular basement membrane immune-complex deposits common in IgG4-TIN
  • Membranous-like GN subset: subepithelial deposits with PLA2R usually negative (helps differentiate from primary membranous)

CLASSIFICATION CRITERIA (ACR/EULAR 2019 + Mayo IgG4-RKD criteria) — combine clinical, serological, imaging and histological features.

Differential

  • Renal cell carcinoma, lymphoma (especially with mass-like lesions)
  • ANCA-associated vasculitis
  • Sarcoidosis (granulomatous, not storiform)
  • Drug-induced TIN
  • Castleman disease
  • Primary membranous nephropathy (PLA2R positive)
  • Lupus nephritis

Management

Induction

  • Prednisolone 0.6 mg/kg/day (typically 30–40 mg) for 2–4 weeks
  • Taper by 5 mg every 2 weeks to 5–10 mg by 3–6 months
  • Calcium + vitamin D; bone protection (bisphosphonate if osteoporosis risk)
  • PCP prophylaxis if prolonged high-dose steroids + additional immunosuppression
  • Gastroprotection

Maintenance

  • Low-dose prednisolone 2.5–5 mg/day for 1–3 years
  • Steroid-sparing agent if relapsing: mycophenolate 1–2 g/day, azathioprine, methotrexate

Rituximab

  • 1 g × 2 doses (2 weeks apart) or 375 mg/m² × 4 weekly doses
  • Indications: relapse, steroid dependence, steroid intolerance, severe multi-organ disease, retroperitoneal fibrosis with aneurysm risk
  • Increasingly used as first-line in severe / aggressive disease
  • Re-treat every 6 months for 2 years in relapsing disease

Follow-up

  • Monitor renal function, ACR, serum IgG4, total IgG, complement, eosinophils
  • Repeat imaging at 3–6 months to confirm response
  • Annual MRA if aortic involvement
  • Lifelong follow-up — relapse rate ~ 30–50% within 3 years

Prognosis

  • Most patients respond to steroids within weeks
  • Early treatment preserves renal function
  • Established fibrosis on biopsy predicts incomplete recovery
  • Aneurysm risk if untreated peri-aortitis

UK CARE PATHWAY: regional nephrology + rheumatology (or specialist IgG4-RD clinic where available) + radiology MDT to differentiate from malignancy.

Interstitial Nephritis
Related reading: Interstitial Nephritis.

Key practical tips

Designed for quick scanning — what to order, what to avoid, sensible portions, common mistakes.

  • Cook from scratch when you can
  • Read sodium labels (≤ 0.3 g per 100 g is low)
  • Take any concerns to your GP or renal team early

Clinical guidance

TL;DR summary

IgG4-RKD: tubulointerstitial nephritis (commonest) or membranous-like GN. Suspect when there are mass-like renal lesions, multi-organ disease (pancreas, salivary glands, orbits), high IgG4, low complement. Steroids are first-line; rituximab for relapse. Most patients respond but relapse is common.

Key takeaways
  • Most common renal lesion: tubulointerstitial nephritis.
  • Look for multi-organ disease and high IgG4.
  • Biopsy: IgG4+ plasma cells + storiform fibrosis.
  • Steroids first-line; rituximab for relapse.
  • Relapse is common — lifelong follow-up.
Kidney Diet & Nutrition Considerations

Diet is one of the most powerful tools you have to look after your kidneys. UK renal guidance points to a Mediterranean-style, reduced-salt pattern: plenty of vegetables, lower-potassium fruit, whole grains, sensible protein, beans and pulses in moderation, oily fish and olive oil. Personal targets — for potassium, phosphate, protein and fluid — should be set by your renal team based on your bloods.

Foods to prioritise

  • Vegetables, lower-potassium fruit and whole grains
  • Sensible portions of fish, eggs, chicken or tofu
  • Olive oil and unsalted nuts in small amounts

Foods to limit

  • Added salt and ultra-processed foods
  • Phosphate additives in processed meats and ready meals
  • Sugary and energy drinks

Potassium, phosphate and protein needs vary between individuals — please confirm personal targets with your renal team or dietitian. Browse the Kidney Diet Hub for more guides in this cluster.

Frequently asked questions

What is IgG4-related kidney disease?

IgG4-related disease (IgG4-RD) is a multi-system fibroinflammatory condition characterised by tumefactive lesions, lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells, storiform fibrosis and obliterative phlebitis. Kidney involvement (IgG4-RKD) most often takes the form of tubulointerstitial nephritis (TIN); a smaller subset develop a membranous-like glomerulonephritis. Other organs commonly involved include the pancreas (autoimmune pancreatitis type 1), salivary glands, orbits, retroperitoneum and aorta.

How is it diagnosed?

Diagnosis combines (1) compatible clinical / imaging features (renal mass-like lesions or diffuse swelling on CT/MRI; multi-organ disease), (2) elevated serum IgG4 (> 1.35 g/L typical; not specific), and (3) characteristic histology on kidney biopsy — dense IgG4-positive plasma cell infiltrate (> 10/HPF and IgG4:IgG ratio > 40%), storiform fibrosis, tubular basement membrane immune complex deposits. Hypocomplementaemia is common in IgG4-RKD (more often than in IgG4-RD overall).

What is the treatment?

First-line is corticosteroids — prednisolone 0.6 mg/kg/day (usually 30–40 mg) for 2–4 weeks, then taper over 3–6 months; many patients need low-dose maintenance for 1–3 years. Rituximab is second-line for relapse, steroid intolerance or contraindication, and is increasingly used early in severe disease. Other agents include mycophenolate, azathioprine and cyclophosphamide. Response is usually rapid but relapse is common, so close follow-up with IgG4 monitoring is essential.

What is the outlook?

Kidney function often improves substantially with treatment, especially when diagnosed early. Established fibrosis on biopsy predicts incomplete recovery. Long-term complications include CKD progression, recurrence in other organs (especially salivary glands, aorta), steroid-induced osteoporosis, diabetes and infection. Lifelong rheumatology / nephrology surveillance is recommended.

What foods are good for kidney health?

A Mediterranean-style, mostly plant-based, reduced-salt diet is the most consistent evidence-based pattern for kidney health. Build meals around vegetables, lower-potassium fruit, whole grains, fish, eggs or tofu, beans and pulses in moderation, and olive oil.

Nutritional challenges in kidney disease

Many people living with kidney disease have to limit foods because of potassium, phosphate, diabetes, dialysis, appetite changes or simply the time it takes to cook from scratch every day. That can make it harder to keep daily nutrition balanced — particularly for vitamins and minerals that food alone may not fully cover.

Kidney Vitality is a UK-formulated daily nutritional support product designed by Consultant Nephrologist Professor Mohammed Mahdi Althaf with renal nutrition in mind from the start. It keeps doses moderate, leaves out added potassium, phosphate and magnesium, and avoids megadose vitamin A — sitting alongside a kidney-friendly diet, not replacing it.

Why Kidney Vitality fits this need

Built around UK guidance

Aligned with the ACR/EULAR 2019 classification criteria, Mayo IgG4-RKD criteria, international IgG4-RD consensus on treatment, and KDIGO guidance on interstitial nephritis.

Designed by a UK Consultant Nephrologist

Formulated and reviewed by Professor Mohammed Mahdi Althaf (GMC 7216325).

Multi-organ and MDT-aware

Practical guidance on imaging mimics, biopsy interpretation, steroid dosing, rituximab use and lifelong relapse surveillance.

Designed by a UK Consultant Nephrologist

Ready to support your kidney health?

If you have been researching kidney health, supplements, CKD nutrition or kidney-friendly living, Kidney Vitality was developed specifically around those principles by Professor Mohammed Mahdi Althaf (GMC 7216325). Nephrologist Developed Daily Multivitamin.

  • No Added Potassium
  • No Added Magnesium
  • No Added Phosphorus
  • No Added Iron
  • One capsule daily
  • UK GMP — BRCGS, NSF GMP, Halal
Subscribe & Save — £20.39/monthCheck your current multivitamin

✓ Free UK tracked delivery  ·  ✓ Delivered every 30 days  ·  ✓ Pause or cancel anytime  ·  ✓ Never run out

ComparisonKidney VitalityTypical high-street multivitamin
Added potassiumNoneOften included
Added phosphateNoneOften included (E338–E452)
Vitamin A (retinol)No megadoseOften high-dose retinol
Kidney-focused formulationYesNo — general population
Consultant Nephrologist involvementYes (GMC 7216325)No
UK GMP manufacturedYes (BRCGS, NSF GMP)Varies

Food supplement. Not a medicine and not a treatment for kidney disease. Speak with your GP, pharmacist or renal team before starting any new supplement, especially in advanced CKD, on dialysis, post-transplant, pregnant or breastfeeding.

Clinical reviewer

Professor Mohammed Mahdi Althaf

Consultant Nephrologist

Acute Physician

GMC 7216325

View Full Biography

Professor Mohammed Mahdi Althaf is a UK Consultant Nephrologist and Acute Physician with a special interest in chronic kidney disease, AKI prevention and renal nutrition. He combines hospital practice with patient education and clinical guidance review.

View professional profile →
View Credentials
  • MD
  • MSc
  • PgDip (Clin Ed)
  • FRCP
  • FHEA
  • FASN

About this article

Written for UK patients and based on:

  • NICE guidance
  • NHS resources
  • British Dietetic Association guidance
  • Kidney Care UK resources
View methodology

Each article is researched against current UK clinical guidance (NICE NG203, NG118, NG136), NHS patient resources, KDIGO and KDOQI international guidelines, and the British Dietetic Association Renal Nutrition Group. Drafts are written by the Kidney Vitality editorial team and reviewed by a UK Consultant Nephrologist before publication. Content is reviewed on a rolling basis and updated when guidance changes.

Editorial standards

  • Clinically reviewed
  • NHS-aligned
  • NICE-aligned
  • Evidence-based
  • Reviewed before publication
View full editorial process

Every article is researched and written by the Kidney Vitality editorial team using current UK clinical guidance (NICE NG203, NG118, NG136), NHS patient resources, KDIGO/KDOQI international guidelines, and British Dietetic Association renal nutrition guidance. Drafts are reviewed for clinical accuracy by Professor Mohammed Mahdi Althaf, MD, MSc, PgDip (Clin Ed), FRCP, FHEA, FASN (Consultant Nephrologist & Acute Physician, GMC 7216325) before publication. Content is updated when UK guidance changes.

References (4)View Sources
  1. NICE NG203: Chronic kidney disease — assessment and management
  2. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD
  3. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update
  4. British Dietetic Association — Renal Nutrition Group

Medical disclaimer

This content is educational only and does not replace personalised medical advice.

Read full disclaimer

This page is general information, not personal medical advice. If you have chronic kidney disease, are on dialysis, have had a kidney transplant, are pregnant or breastfeeding, or take prescription medication, please confirm any supplement with your GP, pharmacist or renal team before starting.

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