Clinical, Biochemical, and Histological Manifestations and Long-Term Outcomes of Renal Sarcoidosis - A Single Center Study

Renal involvement in sarcoidosis is rare. We evaluated the pattern of renal involvement in sarcoidosis, its clinical course, renal histology, and response to treatment. We retrospectively analyzed the data of all cases with sarcoidosis exhibiting renal involvement referred to our department between January 2010 and December 2021. A total of 33 patients (age: 50.6 ± 12.6 years, males: 57.6%) were analyzed. Common presenting symptoms were weight loss (81.8%; n = 27), fever (75.8%; n = 25), and vomiting (63.6%; n = 21). A total of 14 (42.4%) patients had granulomatous interstitial nephritis (GIN), 13 (39.4%) had isolated hypercalcemia, and six (18.2%) had GIN along with hypercalcemia. Renal biopsy was performed in 20 (60.6%) patients, and all showed GIN, with concomitant glomerular disease in four (12.1%) patients. Mean serum creatinine and 24-h urine protein at presentation were 4.3 ± 2.1 mg/dL and 2.5 ± 0.9 g/day, respectively. All patients received oral prednisolone 1 mg/kg/day with subsequent tapering, concomitantly with azathioprine. Mycophenolate mofetil was used in three (9.1%) patients who developed azathioprine-induced hepatoxicity. After a median follow-up of 24 months (8–120 months), mean serum creatinine and 24-h urine protein improved to 1.9 ± 1.5 mg/dL and 1.1 ± 0.6 g/day, respectively, (P = 0.005). On follow-up, two patients (6.1%) became dialysis-dependent, and three (9.1%) succumbed: one due to a cardiovascular event and two to sepsis and septic shock. Granulomatous interstitial nephritis was the most common diagnosis in sarcoidosis patients with kidney failure. Early steroid treatment improves kidney function.