IgG4-related tubulointerstitial nephritis: A prospective analysis.

Aims Immunoglobulin-G4 (IgG4)-related tubulo-interstitial nephritis (IgG4 TIN) 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 IgG4 TIN followed for a minimum period of 1 year or until end-stage renal disease. Results IgG4 TIN 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 IgG4 TIN 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. [ABSTRACT FROM AUTHOR]