Fanconi Syndrome Secondary to Sodium Valproate Therapy: Experience and Literature Review

Fanconi syndrome (FS) can be of primary or secondary origin. Some cases of FS secondary to the use of sodium valproate (VPA) have been described, mostly in children with severe psychomotor retardation who are fed by feeding device. The objetive of this study was to describe patients treated for this entity in our center, comparing them against the published literature.

Descriptive study of our patients and those found in the literature. Epidemiologic and clinical data were collected.

We describe seven patients (three to 17 years old) with severe psychomotor retardation and undergoing treatment with VPA. Four presented pathologic fractures before the diagnosis of FS, and in three patients the diagnosis was reached due to abnormal laboratory findings. A review of the published cases was carried out and, including our sample, a total of 42 patients were studied: 51.3% were male, and the median age at diagnosis of FS was 6 years. Severe psychomotor retardation was found in 92.8% of patients, 78% carried a feeding device, and 77.5% received treatment with several antiepileptic drugs. The mean duration of VPA treatment was 5.7 years (range 2 to 7.5 years). Fifteen patients (37.5%) had bone complications. The resolution time of FS after discontinuation of drug therapy ranged from two to 19 months (median 4 months).

FS related to VPA is a rare complication, but it should be considered in patients with epilepsy, especially if they have severe psychomotor retardation, are users of feeding devices, and receive other antiepileptic treatments in addition to VPA.