Nephrotic syndrome in a multiple sclerosis patient treated with interferon beta 1a.

BACKGROUND: Interferon beta has become standard therapy for reducing relapse frequency in relapsing/remitting Multiple Sclerosis (RRMS). Several different preparations are available including interferon beta 1a (Avonex, Rebif) and interferon beta 1b (Betaferon/Betaseron). For the most part these preparations have been considered safe. Recently there have been concerns relating to liver and now kidney toxicity. CASE REPORT: We present a case of a 28-yr-old male who developed a severe case of nephrotic syndrome while being treated for relapsing/remitting Multiple Sclerosis (RRMS) with weekly injections of interferon beta 1a. SUBSEQUENT COURSE: The nephrosis resolved almost completely once the interferon was stopped and after immunosuppressive treatment. At its peak the daily protein loss was 35.82 g. Kidney biopsy demonstrated membranous glomerulonephritis. DISCUSSION: Two other case reports of nephrotic syndrome have been reported in the literature. This latest (third) report suggests that the safety profile should be reexamined and at least raises the question of potential renal toxicity of interferons in MS.