title: Folate, homocysteine and methionine loading in patients on carbamazepine.
abstract: OBJECTIVE
  Some antiepileptic drugs (AEDs) are associated with low levels of serum (S-FA) and erythrocyte folate (E-FA) and high levels of plasma total homocysteine (p-tHcy). We have explored the concentrations of S-FA, E-FA and p-tHcy in patients on carbamazepine (CBZ). The methionine loading test was applied for better assessment of mildly impaired homocysteine metabolism.
  
  
  METHODS
  The study comprised 42 adult patients on CBZ and 42 matched healthy controls. Blood samples were drawn prior to and 6 h post methionine loading (6 h-PML) (0.1 g/kg body weight).
  
  
  RESULTS
  The patients on CBZ had significantly lower concentrations of fasting S-FA and E-FA than the controls (P=0.0004, P=0.003, respectively). Fasting and 6 h-PML p-tHcy concentrations were significantly higher in the patients than in the controls (P=0.03 and P=0.0001, respectively). The methionine loading test identified additional patients with hyperhomocysteinemia undetected by fasting p-tHcy.
  
  
  CONCLUSIONS
  CBZ therapy may be associated with low folate and high p-tHcy levels.
authors.affiliation: Department of Internal Medicine, Department of Clinical Chemistry and Stavanger Neurological Unit, Rogaland Central Hospital, Stavanger, Norway. apeland@online.no
authors.forename: T
authors.initials: T
authors.lastname: Apeland
authors.forename: M A
authors.initials: MA
authors.lastname: Mansoor
authors.forename: R E
authors.initials: RE
authors.lastname: Strandjord
authors.forename: H
authors.initials: H
authors.lastname: Vefring
authors.forename: O
authors.initials: O
authors.lastname: Kristensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use; D002220:Carbamazepine / Q000009:adverse effects* / Q000627:therapeutic use; D016022:Case-Control Studies; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008715:Methionine / Q000097:blood*; D008875:Middle Aged
chemical_list: D000927:Anticonvulsants; D006710:Homocysteine; D002220:Carbamazepine; D005492:Folic Acid; D008715:Methionine