The effect of levetiracetam and oxcarbazepine monotherapy on thyroid hormones and bone metabolism in children with epilepsy: A prospective study.

Background: Long-term treatment with certain antiepileptic drugs may lead to thyroid function disturbances or alterations in bone metabolism; the data on the effects of new antiepileptic drugs on this are limited and conflicting, especially in children with epilepsy. Therefore, the aim of this study was to investigate the effects of levetiracetam and oxcarbazepine on thyroid hormone levels and bone metabolism in children with epilepsy.

Methods: A total of 51 children with new-onset partial epilepsy were selected. They were randomly treated with either levetiracetam (n = 25), or oxcarbazepine (n = 26) monotherapy. Eight of the 51 patients were excluded for failing to take the drug continuously or failing to undergo a regular review. Thus, 43 patients were finally included (levetiracetam: 23 patients, oxcarbazepine: 20 patients). A control group consisting of age- and sex-matched healthy subjects (n = 20) was included for comparison. Serum triiodothyronine, tetraiodothyronine, free triiodothyronine, free thyroxine, thyroid-stimulating hormone, calcium, phosphorus, alkaline phosphatase, osteocalcin, parathyroid hormone, and 25-hydroxyvitamin D levels and bone mineral density values were measured before and at 6 and 12 months after therapy in all groups.

Results: At baseline, thyroid hormone levels, bone metabolism index, and bone mineral density values did not differ between the control group and the drug-treated groups. Levetiracetam-treated patients showed no significant changes in thyroid hormone levels, bone metabolism, and bone mineral density during the 12-month follow-up period compared with baseline values. In the oxcarbazepine group, compared to baseline values, serum free thyroxine levels decreased after 12 months of treatment (Z = -3.115, p = 0.002), and after 6 and 12 months of treatment, calcium levels decreased (Z = -3.705, p < 0.001 and Z = -3.884, p < 0.001, respectively) and parathyroid hormone levels increased (Z = -3.698, p < 0.001 and Z = -3.921, p < 0.001, respectively); however, all other parameters did not differ from baseline values.

Conclusion: Our data show that levetiracetam treatment has no significant effect on thyroid function and bone metabolism in children with epilepsy. Long-term use of oxcarbazepine may reduce serum free thyroxine levels, resulting in impaired thyroid function, and may reduce serum calcium and increase parathyroid hormone levels, leading to bone metabolism disorders.