Kidneys in the crossfire: insights into renal sarcoidosis

Renal Sarcoidosis is a rare disease and poorly described. We aimed to characterise the clinical presentation, histopathology, treatment response, and renal outcomes in patients with biopsy proven renal sarcoidosis.

A retrospective observational study with biopsy-proven kidney disease in sarcoidosis, assessing demographics, clinical presentation, histology, treatments, and outcomes. Progression to CKD stage 4/5 or requiring dialysis was the primary outcome. Group comparisons and Cox proportional hazards models were used to identify predictors of the primary outcome.

Of the 32 patients, 44% presented with kidney disease. In others, it was noted 2.5 years after diagnosis of extra-renal sarcoidosis. Granulomatous interstitial nephritis was the most common histology seen (59.4%). Steroids were used in 78.1%, predominantly prednisolone; 56% received high-dose regimen (30 mg/day or more). Over a follow up of 6 years, 9 patients experienced CKD 4/5. Patients who developed primary outcome had significantly lower eGFR at the time of presentation to nephrologist (median 20 vs. 43 mL/min, p = 0.049), and in univariate Cox analysis, younger age at diagnosis was associated with primary outcome (HR 0.95, 95% CI 0.91-1.00; p = 0.039). During follow up, 10 (31%) patients developed relapse, 4 (12.5%) patients progressed to ESKD, and 3 (9%) patients died.

Renal sarcoidosis is associated with incomplete renal recovery and carries a substantial risk of progression to advanced CKD or ESKD. Younger age and severe renal impairment at presentation were associated with poor renal outcomes, although these findings should be interpreted with caution. Our findings underscore the need for early diagnosis, structured follow-up, and multicentre prospective registries to refine prognostic tools and guide long-term care.

Not applicable.