Pipecolic acid elevation in plasma and cerebrospinal fluid of two patients with pyridoxine-dependent epilepsy.

Diagnosis of pyridoxine-dependent epilepsy is based on the clinical response to high-dosage application of pyridoxine. Here, we report on 2 patients with pyridoxine-dependent epilepsy with significant elevation of pipecolic acid concentrations in plasma and cerebrospinal fluid (CSF) and further increase of pipecolic acid in CSF during a 72-hour pyridoxine withdrawal in 1 of them. Patients with non-pyridoxine-dependent epilepsy had normal pipecolic acid concentrations in plasma and significantly lower concentrations in CSF. High plasma and CSF pipecolic acid concentrations might provide a diagnostic marker in pyridoxine-dependent epilepsy.