title: Longitudinal change of vitamin D status in children with epilepsy on antiepileptic drugs: prevalence and risk factors.
abstract: BACKGROUND
  Our aim was to evaluate the prevalence and risk factors of vitamin D deficiency and the changes of vitamin D level among children with epilepsy on antiepileptic drugs.
  
  
  METHODS
  The levels of serum 25-hydroxy vitamin D were measured at the start of antiepileptic drugs and at 6- to 12-month intervals in children with epilepsy taking antiepileptic drugs in Pusan National University Children's Hospital. Vitamin D deficiency was defined as 25-hydroxy vitamin D levels <20 ng/mL and insufficiency between 21 and 29 ng/mL.
  
  
  RESULTS
  A total of 143 children (103 boys and 40 girls) with the mean age of 7.4 ± 5.4 years were included. The mean follow-up duration was 1.8 ± 0.8 years. At the start of antiepileptic drugs and the last follow-up, vitamin D deficiency or insufficiency was recognized in 56.6% (81 of 143) and 79.0% (113 of 143), respectively (P < 0.01). The mean value of initial 25-hydroxy vitamin D was 31.1 ± 14.7 ng/mL, which was significantly decreased to 20.2 ± 14.9 ng/mL (P < 0.01) in the last follow-up. Polytherapy (-16.0 ± 13.6 ng/mL), longer duration of ≥2 years (-23.5 ± 9.1 ng/mL), tube feeding (-18.2 ± 14.5 ng/mL), and overweight with body mass index of eighty-fifth percentile or greater (-17.0 ± 12.1 ng/mL) had a significant negative effect for the longitudinal change of 25-hydroxy vitamin D. Age, etiologies, seizure outcomes, and type of antiepileptic drugs (enzyme-inducing versus nonenzyme-inducing antiepileptic drugs) did not affect the longitudinal decrease of 25-hydroxy vitamin D.
  
  
  CONCLUSIONS
  A high proportion of these children on antiepileptic drugs had hypovitaminosis D and a significant decrease between the initial and the last follow-up. Polytherapy and longer duration of antiepileptic drugs, tube feeding, and overweight were independently associated with longitudinally significant decrease of 25-hydroxy vitamin D.
authors.affiliation: Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea.
authors.forename: Yun-Jin
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea.
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Park
authors.affiliation: Department of Pediatrics, Pusan National University Hospital, Busan, Korea.
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Kim
authors.affiliation: Department of Pediatrics, Kosin University Gospel Hospital, Kosin University, Busan, Korea.
authors.forename: Gyu Min
authors.initials: GM
authors.lastname: Yeon
authors.affiliation: Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea. Electronic address: neuroped@naver.com.
authors.forename: Sang Ook
authors.initials: SO
authors.lastname: Nam
mesh_terms: D000293:Adolescent; D000927:Anticonvulsants / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004827:Epilepsy / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D000927:Anticonvulsants; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: antiepileptic drug; child; epilepsy; hypovitaminosis D; vitamin D