title: Effects of antiepileptic drugs on thyroid hormone function in epilepsy patients.
abstract: OBJECTIVE
  Patients with epilepsy are frequently required to take antiepileptic drugs (AEDs) for a long period of time. Many studies have shown that AEDs have a negative influence on endocrine function including the thyroid gland, however the risk factors for the development of low thyroid function in these patients are unclear. This study aimed to determine the potential risk factors of low thyroid function in patients with epilepsy.
  
  
  METHODS
  This was a cross-sectional study including 298 patients with epilepsy. Patients with previous thyroid disease were excluded. Epidemiologic data, type of epilepsy, etiology, the age of seizure onset, duration of epilepsy, intractable epilepsy, and number and dosage of AEDs were recorded. Levels of free thyroxine (fT4) and thyroid stimulating hormone (TSH) were measured.
  
  
  RESULTS
  Fifty-two of the 298 (17.4%) patients had low fT4. Older age (P=0.004), female sex (P=0.014), longer duration of epilepsy (P=0.001), and intractable epilepsy (P=0.009) were significantly associated with low fT4. Regarding individual AEDs, carbamazepine (30.1%), topiramate (28.6%), and levetiracetam (24.3%) were significantly associated with the presence of low fT4. After stepwise logistic regression of all significant variables, female sex, older age, three or more AEDs, and carbamazepine were independent risk factors for low fT4.
  
  
  CONCLUSIONS
  Female patients with epilepsy and an older age, AED polytherapy, and carbamazepine treatment had a higher risk of low fT4. Thyroid function in these patients should be monitored closely.
authors.affiliation: Departments of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Fu-Yuan
authors.initials: FY
authors.lastname: Shih
authors.affiliation: Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Center for Translational Research in Biomedical Sciences, Kaohsiung, Taiwan; Department of Biological Science, National Sun Yet-Sen University, Kaohsiung, Taiwan; Faculty of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yao-Chung
authors.initials: YC
authors.lastname: Chuang
authors.affiliation: Departments of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Ming-Jung
authors.initials: MJ
authors.lastname: Chuang
authors.affiliation: Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Yan-Ting
authors.initials: YT
authors.lastname: Lu
authors.affiliation: Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Wan-Chen
authors.initials: WC
authors.lastname: Tsai
authors.affiliation: Department of Pathology and Laboratory Medicine, Kaohsiung Veteran General Hospital, Kaohsiung, Taiwan.
authors.forename: Ting-Ying
authors.initials: TY
authors.lastname: Fu
authors.affiliation: Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Department of Computer Science and Information Engineering, Cheng Shiu University, Kaohsiung, Taiwan. Electronic address: menghan@cgmh.org.tw.
authors.forename: Meng-Han
authors.initials: MH
authors.lastname: Tsai
mesh_terms: D000328:Adult; D000367:Age Factors; D000927:Anticonvulsants / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D002220:Carbamazepine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D012307:Risk Factors; D012737:Sex Factors; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood
chemical_list: D000927:Anticonvulsants; D013963:Thyroid Hormones; D002220:Carbamazepine; D013972:Thyrotropin; D013974:Thyroxine
keywords: Antiepileptic drugs; Epilepsy; Risk factor; Thyroid function