A 45-year-old woman presented to our hospital for evaluation of chronic kidney disease. Three years earlier, she had been diagnosed at an outside institution with Sjögren’s syndrome after developing sicca symptoms with positive anti-Ro/SSA, antinuclear antibody, and rheumatoid factor titers. Progressive renal insufficiency was noted soon after, but she was lost to follow-up for two years until reestablishing care here, by which time her glomerular filtration rate had declined to 15ml/min.
On exam she was moderately hypertensive but appeared well. Urinalysis was bland with nephrotic proteinuria (3.2g/d); a positive urine anion gap and a low urine osmolal gap despite the presence of non-anion gap acidemia suggested distal renal tubular acidosis. Autoantibody testing was consistent with Sjögren’s syndrome without an overlapping rheumatologic disorder. Hypergammaglobulinemia (with normal IgG4) and borderline hypocomplementemia were noted. MRI/MRA revealed what appeared to be a congenitally atrophic right kidney with right renal artery stenosis, as well as a hypertrophied left kidney with an infiltrated, pseudotumorous appearance.
Left renal biopsy revealed focal tubulitis, diffuse interstitial inflammation with lymphoplasmacytic infiltrate, and collapsing glomerulopathy, together interpreted as Sjögren’s-related renal disease.
Discussion:
Primary Sjögren’s syndrome (SS) is commonly perceived as an infiltrative disorder of exocrine glands, but it should be recognized that the lymphocytic hyperreactivity underlying this process also causes disease within other organs in up to one-third of patients.
Renal involvement is uncommon relative to other extraglandular manifestations of SS, occurring in approximately 10% of cases. Chronic tubulointerstitial nephritis (TIN) is by far the most frequent histologic finding. Patients with SS-TIN can present with electrolyte disturbances, distal or proximal renal tubular acidosis, a concentrating defect, or progressive renal insufficiency; severity can be catastrophic (hypokalemic paralysis, diabetes insipidus, end-stage renal disease) but is more often subclinical.
Glomerular disease is much rarer, usually taking the form of an acute membranoproliferative glomerulonephritis in the context of cryoglobulinemia, or of a membranous nephropathy causing the nephrotic syndrome. Collapsing glomerulopathy has been described in only a handful of SS cases; this patient’s effectively-solitary left kidney likely acted as a maladaptive substrate permitting this unusual development.
Conclusions:
Sjögren’s syndrome is a systemic autoimmune condition not limited to sicca. Providers should recognize the potential for clinically significant tubulointerstitial and glomerular renal disease progressing to end-stage renal failure in patients with SS.