IgG4-related tubulointerstitial nephritis: A prospective analysis

Aims: Immunoglobulin-G4 (IgG4)-related tubulo-interstitial nephritis (IgG4TIN) could be the first presentation of IgG4-related systemic disease. Most of the data is from the West or Japan and retrospective, with good patient outcome. Methods: This study was carried out from April 2011 to July 2013. We report a prospective follow-up of 11 patients who presented with renal dysfunction and had histological diagnosis of IgG4TIN followed for a minimum period of 1 year or until end-stage renal disease. Results: IgG4TIN constituted 0.28% of total renal biopsies and 6.5% of all tubulointerstitial nephritis. Patient ages ranged between 21 and 71 years with a male predominance. All the patients had renal dysfunction at presentation with a mean serum creatinine of 5.12 mg/dL. Proteinuria was subnephrotic except when there was coexisting membranous glomerulonephritis (36.4%). The mean 24-h urine protien excretion was 1.8 g. Serum IgG4 levels were elevated in 10 (90.9%) patients. Ten (90.9%) patients had renomegaly and one (9.1%) had focal renal mass. Extra-renal manifestations were present in seven (63.6%). Renal histology showed pattern A in five (45.5%), pattern B in four (36.3%) and pattern C in two (18.1%) patients. All but one patient (90.9%) received immunosuppressive therapy. Four (36.3%) achieved complete remission and three (27.2%) progressed to end stage renal disease. Two patients died due to infections while on steroid therapy. One patient with a mass had end stage renal disease for 12 months and did not improve with steroid therapy, and one (pattern C) had progressive chronic kidney disease on follow-up. Conclusion: IgG4TIN in an Indian cohort most often presents with rapidly progressive renal failure and less often has extra-renal organ involvement. On follow-up, patients can experience a more aggressive course with progression to end stage renal disease.