title: Homocysteine and its relation to B-vitamins in Graves' disease before and after treatment: effect modification by smoking.
abstract: OBJECTIVE
  To investigate plasma total homocysteine levels and its relation to B-vitamins and smoking in Graves' disease before and after antithyroid therapy.
  
  
  METHODS
  A longitudinal study taking place at four hospitals in Norway.
  
  
  METHODS
  Plasma total homocysteine, serum folate, serum cobalamin and riboflavin, flavin mononucleotide and flavin adenine dinucleotide in plasma were investigated in 182 patients with hyperthyroidism before treatment. The same parameters were reinvestigated in 112 of these patients after attaining euthyroid state.
  
  
  RESULTS
  In hyperthyroidism, plasma total homocysteine was low, and inversely related to folate, cobalamin and riboflavin, and positively related to serum creatinine and age. Following antithyroid therapy, total homocysteine increased and the concentration of folate, cobalamin, riboflavin, flavin mononucleotide and flavin adenine dinucleotide decreased significantly. The most pronounced reduction (35%) was observed for flavin mononucleotide. In the hyperthyroid state, smokers had lower levels of folate and flavin mononucleotide than non-smokers. After restoration of euthyroidism, both folate and riboflavin were significantly lower in smokers than non-smokers. Plasma total homocysteine increased according to decreasing quartiles of B-vitamins. For riboflavin, this relation was confined to smokers.
  
  
  CONCLUSIONS
  Plasma total homocysteine changes according to thyroid status. These changes may be partly attributable to altered folate, cobalamin but also riboflavin status, particularly in smokers.
authors.affiliation: LOCUS for Homocysteine and Related Vitamins, University of Bergen, Haukeland University Hospital, Bergen, Norway. bjorn.nedrebo@ikb.uib.no
authors.forename: B G
authors.initials: BG
authors.lastname: Nedrebø
authors.forename: S
authors.initials: S
authors.lastname: Hustad
authors.forename: J
authors.initials: J
authors.lastname: Schneede
authors.forename: P M
authors.initials: PM
authors.lastname: Ueland
authors.forename: S E
authors.initials: SE
authors.lastname: Vollset
authors.forename: P I
authors.initials: PI
authors.lastname: Holm
authors.forename: S
authors.initials: S
authors.lastname: Aanderud
authors.forename: E A
authors.initials: EA
authors.lastname: Lien
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D013956:Antithyroid Agents / Q000627:therapeutic use*; D002231:Carbimazole / Q000627:therapeutic use; D003404:Creatinine / Q000097:blood; D005260:Female; D005492:Folic Acid / Q000097:blood; D006111:Graves Disease / Q000097:blood* / Q000188:drug therapy; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012256:Riboflavin / Q000097:blood; D012907:Smoking / Q000097:blood*; D014805:Vitamin B 12 / Q000097:blood; D014803:Vitamin B Complex / Q000097:blood*
chemical_list: D013956:Antithyroid Agents; D006710:Homocysteine; D014803:Vitamin B Complex; D002231:Carbimazole; D005492:Folic Acid; D003404:Creatinine; D014805:Vitamin B 12; D012256:Riboflavin