[Interstitial nephropathies in sarcoidosis. Effect of corticosteroid therapy and long-term evolution. Retrospective study of 22 cases].

Interstitial Nephritis (IN) with or without epithelioid granulomas is the most frequent form of renal impairment in sarcoidosis. Nevertheless, few studies have provided conclusions about its treatment and long-term outcome. We report 22 cases collected over a 20-year period in 9 nephrologic departments of the west of France. We discuss the criteria which permit sarcoidosis to be distinguished from other causes, particularly of IN drugs. Twenty patients were treated with corticoids. In 18 the result could be evaluated on at least 12 months. In 11 there was a decrease of plasma creatinine (Pc) and in 8 of these cases this decrease reached 50%. Of the 12 who were followed from 1 to 17 years, 4 obtained a reduction of Pc of at least 50%. These improvements occurred even in patients whose Pc was initially higher than 300 mumol/l. Only 2 patients reached end-stage renal failure and hemodialysis within the observation period, one as early as the first month, the other after 6 years. Five relapses were observed after stopping treatment but 4 responded again favorably upon resumption. Two patients who received no treatment at all nevertheless had stabilization or improvement of their renal function with a follow-up of 5 years for one case. It may be concluded that the long-term prognosis of sarcoidosis IN can be fairly good but there is no proof that it depends mainly on corticosteroid therapy.