The Role of Carnitine Monitoring and Supplementation in Children With Epilepsy on a Ketogenic Diet

ObjectiveThere has been limited research on carnitine levels, supplementation, and the ketogenic diet.MethodsOver 8 years, 150 consecutive children treated with the ketogenic diet at Johns Hopkins Hospital were evaluated and information about carnitine levels and use obtained.ResultsOne hundred five (70%) had carnitine levels checked. The mean total carnitine level at first follow-up was 56 µmol/L (standard deviation [SD] 32) (normal range 30-60 µmol/L) and free 26 (SD 19) µmol/L (normal range 22-52 µmol/L). In those not supplemented with carnitine, total carnitine was stable (46.2 [SD 12] to 44.9 [SD 19] µmol/L, P = .80), whereas free carnitine decreased (35.8 [SD 12] to 20.1 [SD 11] µmol/L, P < .001). Those on valproate had lower baseline total carnitine levels (40.7 [SD 20] vs 52.0 [SD 15] µmol/L, P = .02). At 3 months, 83% with normal total carnitine levels (>30 µmol/L) had >50% seizure reduction compared to 60% with hypocarnitinemia (P = .06). Carnitine was supplemented in 36 (24%), typically in those older, on higher ketogenic ratios, prior to 2020, and with longer ketogenic diet durations. Twelve (33%) had documented benefit from carnitine supplementation, but there was no group difference in seizure control or ketosis.ConclusionsIn this single-center study, hypocarnitinemia was seen at baseline in those on valproate and decreased free carnitine levels occurred over time. Those with higher total carnitine levels at 3 months were slightly more likely to be improved. Carnitine was supplemented in one-quarter of patients, with 1 of 3 showing modest benefit in ketosis and seizures.