Renal involvement in sarcoidosis

Introduction Sarcoidosis is a systemic granulomatosis that affects the lungs and mediastinum. Renal involvement is rare in this disease. It's most commonly granulomatous interstitial nephritis. The most common form of presentation is naked renal failure. Description This is a retrospective study that collected 12 cases of sarcoidosis complicated by acute renal failure. The study consisted of identifying the epidemiological, clinical, biological and histologic data that confirmed the diagnosis from January 1994 to January 2016. A search for extra-renal placement of sarcoidosis concerned all cases. Then, a study of the therapeutic and evolutionary profile was carried out in all cases. Methods Twelve patients (8 males and 4 females) with a mean age of 43 years. The intradermal tuberculin reaction sit negative in 6 cases. Biological analysis showed acute renal failure with a median creatinine of 54.32 mg/L, biological inflammatory syndrome in all cases, normal blood calcium in 9 cases, hypercalcaemia in 6 cases, hypercalciuria in 4 cases, hypergammaglobulinemia of polyclonal appearance in 3 cases and elevated proteinuria in 2 cases. Renal ultrasound was normal in all patients. The renal biopsy performed in all cases showed tubulointerstitial nephropathy. The extra-renal signs found were pulmonary interstitial syndrome in 4 cases, dry syndrome in 4 cases, mediastinal lymphadenopathy in 4 cases, one patient presented a unilateral uveitis. Two patients underwent extra-renal treatment. All patients were on corticosteroids with a clear improvement in creatinine and normalisation of renal function in all patients. The average follow-up time was 18 months. Renal involvement during sarcoidosis is rare (10%) but may progress to renal failure (3% of cases). The renal biopsy is of great interest to maintain the diagnosis of sarcoidosis, especially in the absence of other extra-renal signs. Conclusion Renal involvement during sarcoidosis is rarely revealing and may delay diagnosis, leading to chronic and even end-stage renal disease.