Clinical and pathological features of kidney involvement in Sjogren’s disease: case series

Aim: To describe three cases of kidney involvement in patients with Sjögren's disease (SjD) who underwent kidney biopsy.

Methods: Medical records from three patients with SjD were analyzed. The diagnosis of SjD was established according to the 2016 ACR/EULAR criteria.

Results: The first patient (33 years old) with primary SjD presented with distal renal tubular acidosis (urine pH 8.0, urine SG 1.007; blood pH 7.27, blood HCO3- – 15.1 mmol/L, potassium 3.0 mmol/L, chloride 116 mmol/L), elevated serum creatinine level (127 µmol/L; eGFR by CKD-EPI 46 mL/min/1.73 m²) and nephrolithiasis (carbonate apatite and struvite). Kidney biopsy revealed focal glomerulosclerosis, minimal interstitial changes, and renal calcinosis. In the absence of immunological activity of SjD, no indications for escalating immunosuppressive therapy was identified.

The second patient (40 years old) had SjD associated with rheumatoid arthritis. Laboratory findings included serum creatinine 152 µmol/L (eGFR by CKD-EPI 38 mL/min/1.73 m²), proteinuria (0.69 g/24h), leukocyturia (25 cells/HPF), urine pH 7.0, and metabolic acidosis (blood pH 7.24, HCO3- 16.1 mmol/L) consistent with distal renal tubular acidosis. Kidney biopsy confirmed chronic tubulointerstitial nephritis with medullary calcinosis and no evidence of glomerular injury. Given active systemic disease, escalation of immunosuppressive therapy was initiated.

The third patient (69 years old) with an overlap syndrome (systemic sclerosis, primary biliary cholangitis, and SjD), presented an elevated serum creatinine up to 207 µmol/L (eGFR by CKD-EPI 20 mL/min/1.73 m²), minimal urinalysis abnormalities (proteinuria 0.33 g/L, leukocyturia 5-7 cells/HPF, urine pH 5.0, SG 1.020). Serum creatinine subsequently increased to 335 µmol/L, consistent with acute kidney injury. Kidney biopsy showed acute tubular injury without inflammatory changes, excluding SjD-related renal involvement and preventing unnecessary immunosuppressive therapy.

Conclusion. The cases illustrate the heterogeneity of kidney involvement in SjD. Kidney biopsy is essential for defining the type of renal lesion and guiding appropriate therapeutic decisions.

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