Effects of Treatment on Endocrine Function in Patients with Epilepsy

Antiepileptic drug (AED) treatment is associated with multiple short- and long-term side effects. Effects on endocrine function, including weight change, reproductive function, thyroid function, and bone health are examples of these side effects. Some AEDs affect weight, resulting in weight gain or loss. Levetiracetam and lamotrigine are weight-neutral agents, whereas valproate is associated with weight gain. Reproductive dysfunction is reported in women and men with epilepsy treated with AEDs. In women, the most common symptoms are hyperandrogenism, menstrual disorders with ovulatory failure, polycystic ovary-appearing ovaries or polycystic ovary syndrome, and hyperinsulinemia. These symptoms may be secondary to epilepsy or to AED treatment, particularly with valproate. In men, effects on sperm quality and motility, delayed sexual development, and small testicular size have been described in association with AED treatment. Carbamazepine reduces testosterone levels, whereas valproate increases androgen levels. Oxcarbazepine is not associated with changes in testosterone levels. Treatment with all of these agents can result in changes in sperm, including concentration, morphology, and motility. Enzyme-inducing AEDs are known to result in decreased thyroid hormones. Recent studies found reduced serum thyroid hormone concentrations in men and young girls treated with carbamazepine and oxcarbazepine. However, all patients were clinically euthyroid, and these changes were reversible after AED withdrawal. Persons with epilepsy treated with AEDs are at increased risk for fracture. Not only is this increased because of seizure activity, but also because of treatment with AEDs. AED treatment results in decreased bone mineral density, the most sensitive predictor of fracture and changes in biochemical indices of bone metabolism, including calcium, vitamin D, and markers of bone formation and resorption. Identifying each of these endocrine abnormalities is important because it may be necessary and beneficial to change AED treatment. In addition, multiple therapies exist for the treatment of polycystic ovary syndrome, infertility, and decreased bone mineral density.