Sjögren's syndrome - not just Sicca: renal involvement in Sjögren's syndrome

Objective: To present a case of severe interstitial nephritis with proteinuria in primary Sjögren's syndrome (pSS) and review the literature regarding renal disease and its management in pSS, aiming to suggest recommendations for treatment. Methods: A search of MEDLINE (PubMed) was performed for review articles and case reports using the MESH terms: Sjögren syndrome; renal disease; interstitial nephritis (IN); glomerulonephritis (GN). Results: We describe a rare case of pSS presenting with hypokalaemic tetraparesis and proteinuria due to severe IN, successfully treated with high-dose steroids and azathioprine. Reviewing the literature, we identified 180 reported cases of renal involvement in pSS (selected based on the European criteria for pSS), 89 of which underwent renal biopsies revealing IN in 49 cases, GN in 33 samples, and both IN and GN in seven. Eighteen studies reported treatment experience of renal disease in 32 pSS cases. Seventeen patients were treated with corticosteroids and cyclophosphamide, and 15 patients received only steroids with improvement in the majority of cases. Conclusion: The present case, as well as the limited number of reports in the literature, suggest that renal involvement, including IN, in pSS may improve with immunosuppressive therapy. Further studies are required to determine indications for and dosages of immunosuppressive treatment in patients with renal involvement of pSS.