Carnitine Levels in Valproic Acid-Treated Psychiatric Patients: A Cross-Sectional Study
J Clin Psychiatry 2005(5);66(5):555-558
© Copyright 2014 Physicians Postgraduate Press, Inc.
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Background: Carnitine facilitates the transport
of long-chain fatty acids across the mitochondria for beta
oxidation, and the removal of potentially toxic acylcoenzyme-A
metabolites from the inner aspect of mitochondrion as
acylcarnitines. Previous studies suggest a significant decrease
in carnitine concentrations and changes in the ratio of
acylcarnitine to free carnitine in seizure-disordered patients
treated with valproic acid (VPA), which may lead to clinical
manifestations of carnitine deficiency. This study sought to
explore whether the same decrease in plasma free carnitine and
increase in acylcarnitines are seen when VPA is used in the
treatment of patients with psychiatric disease.
Method: Thirty psychiatric patients treated with
VPA for at least 6 months were selected for the study and granted
informed consent for participation. Exclusion criteria included
liver disorder or pancreatitis, metabolic defects known to affect
plasma carnitine levels, or noncompliance with VPA regimen.
Plasma free carnitine, total carnitine, acylcarnitine, VPA, and
amylase levels were determined, and liver function tests (LFTs)
were performed. Pearson correlations were conducted between VPA
levels, levels and ratios of carnitines, as well as LFTs and
Results: Plasma free and total carnitine levels
were lower than the reported normal range for the laboratory
performing the assay, and the ratio of acylcarnitine to free
carnitine was increased. There was a significant positive
correlation of VPA levels and acylcarnitine-free carnitine ratio,
a trend toward significance between VPA levels and acylcarnitine
levels, and a marginal negative correlation between VPA levels
and free carnitine levels. VPA levels correlated also with
several LFTs and acylcarnitine levels. Octanoyl carnitine and
acylcarnitine levels, as well as acylcarnitine-free carnitine and
octanoyl-free carnitine ratios, correlated significantly with
Conclusion: Although the study was limited by a
cross-sectional design without direct control comparison, the
findings suggest that patients with various psychiatric
conditions treated with polypharmacy that includes VPA may have
lower plasma carnitine levels than would be expected in healthy