Fanconi Syndrome Caused by Valproic Acid

Two severely disabled children with epilepsy, a 6-year-old boy and a 15-year-old girl, had been treated with valproic acid from the ages of 5 and 6 months, respectively, and developed Fanconi syndrome. Both patients were bedridden and fed by means of a nasogastric or gastrostomy tube. Because their Fanconi syndrome appeared to be caused by valproic acid, that treatment was stopped; for both patients, the Fanconi syndrome then resolved, in 6 months and 3 months, respectively. Severely handicapped children may be at risk for valproic acid-induced renal involvement. Although renal involvement is an uncommon adverse effect of valproic acid, Fanconi syndrome due to valproic acid therapy has rarely been reported. In the few previous cases, the patients, who were bedridden and fed through a nasogastric or a gastrostomy tube, had taken valproic acid for an average of approximately 7 years. Nonetheless, their valproic acid blood levels were normal. Urinary abnormalities disappeared in an average of 4 months, as also in the present two cases. The potential for Fanconi syndrome must be considered in children with epilepsy who are treated with valproic acid, especially in severely disabled children.