Background: Valproic acid (VPA), a widely used antiepileptic drug, has broad-spectrum activity against both generalized and partial epilepsy. Among the side effects of VPA, weight gain is frequently reported, although the real incidence and magnitude of this problem is unknown. Its pathogenesis is most likely multifactorial, and is controversial. Methods: In order to evaluate the role of hyperinsulinemia and related hormonal abnormalities in VPA-induced obesity, data from the existing literature have been analyzed and discussed critically. Results: Patients suffering from weight gain show various metabolic and endocrinologic abnormalities. The most frequent are hyperinsulinemia and insulin resistance, hyperleptinemia and leptin resistance, and an increase in the availability of long-chain free fatty acids. Significant weight gain is associated with increased levels of insulin and leptin, suggesting a close relationship between obesity-induced hyperinsulinemia and hyperleptinemia. VPA can directly stimulate pancreatic β-cells and indirectly enhance insulin resistance by suppressing insulin-mediated peripheral glucose uptake. Leptin activation seems to be similar in obese VPA-treated subjects to that seen in otherwise obese subjects. Conclusions: The mechanisms of hyperinsulinemia in VPA-induced weight gain remain unclear, although it is likely that obesity is the cause of hyperinsulinemia and all related metabolic changes. However, this heterogeneous metabolic disorder requires further research.

Valproic acid (VPA) is effective for the treatment of many types of epilepsy, but its use can be associated with an increase in body weight. We report a case of nonalcoholic fatty liver disease (NAFLD) arising in a child who developed obesity during VPA treatment. Laboratory data revealed hyperinsulinemia with insulin resistance. After the withdrawal of VPA therapy, our patient showed a significant weight loss, a decrease of body mass index, and normalization of metabolic and endocrine parameters; moreover, ultrasound measurements showed a complete normalization. The present case suggests that obesity, hyperinsulinemia, insulin resistance, and long-term treatment with VPA may be all associated with the development of NAFLD; this side effect is reversible after VPA withdrawal.

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