Longterm treatment of psoriasis using fumaric acid preparations can be associated with severe proximal tubular damage

Fumaric acid preparations are used as longterm and effective treatment of psoriasis. Apart from gastrointestinal, dermatological and hematological side-effects, transient renal damage was observed during treatment with fumaric acid. The case of a 38 year old woman who was treated with fumaric acid (420 mg bid) for 5 years before she complained of fatigue and weakness. According to clinical laboratory she had developed severe proximal tubular damage. Hypophosphatemia, glycosuria and proteinuria persisted although medication was stopped immediately.