The effect of antiepileptic drugs on thyroid hormonal function: valproic acid and phenobarbital

  • Olcay Güngör
  • Ahmet Kağan Özkaya
  • Fatih Temiz


The aim of this study was to evaluate the thyroid function alterations in a group of epileptic children taking antiepileptic drugs. The study included a total of 183 pediatric epilepsy patients, aged 15 months—16 years, comprising 114 patients treated with valproic acid, 69 patients treated with phenobarbital, and 151 age-matched healthy volunteers as the control group. Serum levels of thyroid hormones were measured before the beginning of the antiepileptic therapy and after 12 months of treatment. Thyroid-stimulating hormone levels were significantly higher in the 12th month of phenobarbital and valproic acid treatment. The level of free triiodothyronine before treatment was higher in epileptic patients than in the control group. Subclinical hypothyroidism at month 12 was determined in 15.2% of the valproic acid group and in 2.9% of the phenobarbital group. When compared with the pre-treatment values, there was a statistically significant difference in the incidence of subclinical hypothyroid in the valproic acid group and no significant difference in the phenobarbital group. Symptomatic hypothyroidism was not detected. It was concluded that the thyroid functions of patients using valproic acid and phenobarbital for a long time should be regularly monitored.


Children Phenobarbital Thyroid functions Valproic acid 


Author contribution

O.G. initiated the study, and contributed to design of the study, interpretation of the results, and writing the manuscript. F.T. participated in data collection and contributed to interpretation of the results. A.K.Ö. initiated and designed study, and A.K.Ö. contributed to statistical analysis, interpretation of the results, and writing the manuscript. All the authors critically revised the article and approved the final article as submitted.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from the parents or legal guardians of each participant included in the study.


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Copyright information

© Belgian Neurological Society 2018

Authors and Affiliations

  • Olcay Güngör
    • 1
  • Ahmet Kağan Özkaya
    • 2
  • Fatih Temiz
    • 3
  1. 1.Department of Pediatric Neurology, Faculty of MedicineKahramanmaras Sutcu Imam UniversityKahramanmarasTurkey
  2. 2.Department of Pediatric EmergencyUniversity of Health Science Kanuni Training and Research HospitalTrabzonTurkey
  3. 3.Department of Pediatric Endocrine, Faculty of MedicineKahramanmaras Sutcu Imam UniversityKahramanmarasTurkey

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