title: An examination of the mutual effects of valproic acid, carbamazepine, and phenobarbital on 25-hydroxyvitamin D levels and thyroid function tests.
abstract: BACKGROUND
  The effects of antiepileptic drugs (AEDs) on bone metabolism and the endocrine system are not fully known, and publications on the subject are inconsistent.
  
  
  OBJECTIVE
  The study aimed to examine the mutual effects of valproic acid (VPA), carbamazepine (CBZ), and phenobarbital (PB)-AEDs frequently used in childhood-on bone mineral metabolism and thyroid function tests.
  
  
  METHODS
  Children monitored with a diagnosis of idiopathic epilepsy by the pediatric neurology clinic, using AEDs for at least 6 months and with episodes under control, were included in the study. Patients were divided into groups on the basis of the drugs used. Thyroid function tests and 25-hydroxyvitamin D or 25(OH)D levels were measured from blood specimens. The data obtained were then compared with those of the control group.
  
  
  RESULTS
  A significantly high level of subclinical hypothyroidism was seen in patients using VPA (p < 0.001). There was no significant difference between any of the three study groups and the control group in terms of 25(OH)D (p > 0.05).
  
  
  CONCLUSIONS
  Pediatric patients using AEDs, particularly VPA, should be monitored for subclinical hypothyroidism. VPA, CBZ, and PB have no effect on vitamin D levels.
authors.affiliation: Department of Pediatric Neurology, Faculty of Medicine, Ataturk University, Erzurum, Turkey.
authors.forename: Mehmet Ibrahim
authors.initials: MI
authors.lastname: Turan
authors.affiliation: Department of Pediatric Endocrinology, Faculty of Medicine, Ataturk University, Erzurum, Turkey.
authors.forename: Atilla
authors.initials: A
authors.lastname: Cayir
authors.affiliation: Department of Pediatric Neurology, Faculty of Medicine, Ataturk University, Erzurum, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Ozden
authors.affiliation: Department of Pediatric Neurology, Faculty of Medicine, Ataturk University, Erzurum, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Tan
mesh_terms: D000927:Anticonvulsants / Q000009:adverse effects*; D002220:Carbamazepine / Q000009:adverse effects*; D002648:Child; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000139:chemically induced; D008297:Male; D010634:Phenobarbital / Q000009:adverse effects*; D013960:Thyroid Function Tests; D014635:Valproic Acid / Q000009:adverse effects*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D000927:Anticonvulsants; D014807:Vitamin D; D002220:Carbamazepine; D014635:Valproic Acid; C104450:25-hydroxyvitamin D; D010634:Phenobarbital