Copper availability and NAFLD in epileptic patients treated with valproic acid 153 59.4 ± 2.5 mg/L (56.5 mg/L)), suggesting that throm- bocytopenia in these cases was not mediated by direct drug toxicity on the blood platelets. However, a VPA- induced formation of autoantibodies against platelets is possible (41), and the results obtained for the MPV and PDW indices in our patients are compatible with a hyper-destruction or reduced circulating platelet survival, similar to that seen in immune thrombocy- topenia. If this assumption is correct, the APRI and FIB-4 scores would be falsely increased, at least in some cases, reinforcing the suggestion expressed above that in the studied group of VPA-treated patients there is no signiﬁcant liver ﬁbrosis. With regard to these results, the recently described in-vitro and in-vivo inhibitory effect of VPA on the hepatic stellate cell activation, and consequently on ﬁbrosis development in chronically injured mouse liver (42), should be considered. Unfortunately a diagnosis of non-alcoholic fatty liver disease by ultrasonography was not carried out in our study. In any case, the results we have obtained suggest that the decreased copper availability present in the epileptic patients treated with VPA is not associated with fatty liver disease. Copper status is linked to iron homeostasis, and copper deﬁciency causes hepatic iron accumulation that is frequently associated with hepatic steatosis (12). Increased liver iron can promote oxidative stress and insulin resis- tance; however, these processes may be modulated by haptoglobin polymorphism, and Hp2-2 phenotype would be a risk factor for metabolic syndrome and non-alcoholic fatty liver disease (43). The association between copper availability, iron metabolism, hapto- globin polymorphism, and metabolic syndrome requires clariﬁcation. Declaration of interest: One of the authors (NL) received a grant from the Sociedad Española de Bioquímica Clínicay Biología Molecular. The authors report no conﬂicts of interest. References 1. Gertsner T, Bell N, Köning S. Oral valproic acid for epilepsy- long term experience in therapy and side effects. Expert Opin Pharmacother. 2008;9:285–92. 2. Nalivaeva NN, Belyaev ND, Turner AJ. Sodium valproate: an old drug with new roles. Trends Pharmacol Sci. 2009;30: 509–14. 3. Chateviaux S, Morceau F, Dicato M, Diederich. Molecular and therapeutic potential and toxicity of valproic acid. J Biomed Biotechnol. 2010;2010:pii 479364. 4. Donato MT, Martinez-Romero A, Jimenez N, Negro A, Herrera G, Castell JV, et al. Cytometric analysis for drug- induced steatosis in HepG2 cells. Chem Biol Interact. 2009; 181:417–23. 5. Cotariu D, Zaldman JL. Valproic acid. Clin Chem. 1988;34: 890–7. 6. Luef GJ, Waldmann M, Sturm W, Naser A, Trinka E, Unterberger I, et al. Valproate therapy and non-alcoholic liver disease. Ann Neurol. 2004;55:729–32. 7. Luef G, Rauchenzauner M, Waldmann M, Sturn W, Sandhofer A, Seppi K, et al. Non-alcoholic fatty liver disease (NAFLD), insulin resistance and lipid proﬁle in antiepileptic drug treatment. Epilepsy Res. 2009;86:42–7. 8. Aires CCP, Ijlst L, Stet F, Prip-Buus C, Tavares de Almeida I, Duran M, et al. Inhibition of hepatic palmitoyl-trasnferase I (CPT IA) by valproyl-CoA as a possible mechanism of valproate-induced steatosis. Biochem Pharmacol. 2010;79: 792–9. 9. Tutor-Crespo MJ, Hermida J, Tutor JC. Assessment of copper status in epileptic patients treated with anticonvulsant drugs by measuring the speciﬁc oxidase activity of ceruloplasmin. Epi- lepsy Res. 2003;56:147–53. 10. Kuzuya T, Amioka K, Nabeshima T. Valproic acid increases biliary copper excretion in the rat. Epilepsy Res. 2002;51: 279–85. 11. Lampón N, Tutor JC. Effect of valproic acid treatment on copper availability in adult epileptic patients. Clin Biochem. 2010;43:1074–8. 12. Aigner E, Theurl I, Haufe H, Seifert M, Hohla F, Scharinger L, et al. Copper availability contributes to iron perturbations in human non-alcoholic fatty liver disease. Gastroenterol. 2008;135:680–8. 13. Aigner E, Strasser M, Haufe H, Sonnweber T, Hohla F, Stadlmayr A, et al. A role for low hepatic copper concentra- tions in non-alcoholic fatty liver disease. Am J Gastroenterol. 2010;105:1978–85. 14. Geubel AP, Gregoire V, Rahier J, Lissens W, Dive C. Hypo- ceruloplasminemia and ultrastructural changes resembling Wilson’s disease in non-alcoholic liver steatosis. A clinical and pathological study of ﬁve cases. Liver. 1988;8:299–306. 15. Clark JM, Brancati FL, Diehl AM. The prevalence and etiology of elevated aminotransferase levels in the United States. Am J Gastroenterol. 2003;98:960–7. 16. Kirovski G, Schacherer D, Wobser H, Huber H, Niessen C, Beer C, et al. Prevalence of ultrasound-diagnosed non-alco- holic fatty liver disease in a hospital cohort and its association with anthropometric, biochemical and sonograﬁc character- istics. Int J Clin Exp Med. 2010;3:202–10. 17. Koda M, Kawakami M, Murawaki Y, Senda M. The impact of visceral fat in nonalcoholic fatty liver disease: cross-sectional and longitudinal Studies. J Gastroenterol. 2007;42:97–103. 18. de Abreu MRA, Ramos APP, Vendramini RC, Brunetti IL, Pepato MT. Steatosis and hepatic markers before and shortly after bariatric surgery. Ann Clin Biochem. 2007;44:63–9. 19. Musso G, Gambino R, Durazzo M, Cassader M. Noninvasive assessment of liver disease severity with liver fat score and CK-18 in NAFLD: prognostic value of liver fat equation goes beyond hepatic fat estimation. Hepatology. 2010;51:715–17. 20. Neuschwander-Tetri BA, Clark JM, Bass NM, Van Natta ML, Unalp-Arida A, Tonascia, et al. Clinical, labora- tory and histological associations in adults with nanalcoholic fatty liver disease. Gastroenterology. 2010;52:913–24. 21. Nomura F, Ohnishi K, Koen H, Hiyama Y, Nakayama T, Itoh Y, et al. Serum cholinesterase in patients with fatty liver. J Clin Gastroenterol. 1986;8:599–602. 22. Iwasaki T, Yoneda M, Nakajima A, Terauchi Y. Serum butyrylcholinesterase is strongly associated with adiposity, the serum lipid proﬁle and insulin resistance. Intern Med. 2007;46:1633–9.