# Renal Involvement in Primary Sjögren's Syndrome: A Multi-centric Study From North India

## TL;DR

This study from North India highlights that kidney problems are common in Sjögren's syndrome and often go undetected, stressing the need for early kidney screening.

## Contribution

The study provides new insights into the frequency and types of renal involvement in primary Sjögren's syndrome in a North Indian population.

## Key findings

- Chronic tubulointerstitial nephritis was the most common renal pathology observed.
- Most patients were diagnosed at advanced stages of kidney disease.
- Over half of the patients received immunosuppressive therapy, primarily steroids.

## Abstract

Introduction

Renal involvement in primary Sjögren's syndrome is often underdiagnosed and overlooked. There is a lack of substantial data on the renal manifestations and outcomes in these patients. This study aims to stress the importance of thorough evaluation of renal dysfunction in individuals with Sjögren's syndrome to improve their overall health and quality of life.

Methods

This multicentric, retrospective study analyzed patients with renal involvement in Primary Sjögren's syndrome from 2013 to 2021. Clinical profiles of those affected by primary Sjögren's syndrome and renal involvement were examined. Patients were enrolled based on specific inclusion criteria, and relevant biochemical tests and kidney biopsy results were reviewed. One-year follow-up data was also included.

Results

A total of 38 patients were studied, with a strong female predominance (N=36, 94.7%) and a mean age of 41.4 ± 14.08 years. Reduced estimated glomerular filteration rate (eGFR; <60 ml/min/1.73 m²) was found in 24 patients (63%), while seven (18.4%) were diagnosed with nephrotic syndrome, another seven (18.4%) had sub-nephrotic range proteinuria, and four (10.5%) presented with microscopic hematuria. Two patients (5.2%) were already on maintenance hemodialysis when diagnosed with Sjögren's syndrome, and one patient was identified post-kidney transplant. Renal biopsies revealed various pathological findings, with chronic tubulointerstitial nephritis being the most common (N=4/11, 36.3%). Immunosuppressive therapy was given to 20 patients (56%), primarily steroids alone (N=8, 21%), while others received conservative management and supportive care.

Conclusion

Chronic tubulointerstitial nephritis is the most frequent form of renal involvement in Primary Sjögren's syndrome, with most cases diagnosed at advanced stages of kidney disease. This study underscores the importance of early and comprehensive renal evaluations in patients with Sjögren's syndrome, as early detection and timely treatment may help prevent progression to chronic kidney disease.

Learning points

Screening for renal involvement in primary Sjögren's syndrome (pSS) should include urinalysis, serum creatinine levels, and kidney biopsy when appropriate. A kidney biopsy showing characteristic findings, such as tubulointerstitial nephritis (TIN), should be considered an additional supportive criterion for the classification of pSS, as it can influence both treatment decisions and renal outcomes.