Deferasirox treatment may be associated with reversible renal Fanconi syndrome

Two cases of reversible renal Fanconi syndrome associated with deferasirox treatment are reported. One of these recurred upon rechallenge. Deferasirox (Exjade®) is a new once daily oral iron chelator for the treatment of chronic iron overload due to blood transfusions. Deferasirox became available in the USA in 2005 and is licensed in over 70 countries worldwide [1]. Preclinical studies in animals indicated that the kidney was a potential target organ of toxicity [2]. However, in phase II and III clinical trials, deferasirox was found to be generally well tolerated [3-5]. Cases of fatal, acute, irreversible renal failure have been described in a post marketing report on deferasirox [6], but details of the incidence rate or cause of these adverse events have not yet been reported, raising concerns regarding the toxicity of the drug. Renal Fanconi syndrome is a rare disorder in which the proximal tubular function of the kidney is impaired, resulting in decreased reabsorption of electrolytes and nutrients into the bloodstream. The solutes involved include glucose, amino acids, uric acid, phosphate, and bicarbonate. Both patients described below, having transfusion related iron overload, developed renal tubular dysfunction.