title: Potential association of thyrotoxicosis with vitamin B and folate deficiencies, resulting in risk for hyperhomocysteinemia and subsequent thromboembolic events.
abstract: OBJECTIVE
  To describe a patient with severe thyrotoxicosis attributable to Graves' disease who had a thrombotic cerebrovascular accident and hyperhomocysteinuria, which resolved on correction of the thyrotoxicosis, and to present findings in a pilot study undertaken to investigate the relationship among thyrotoxicosis, homocysteine, folate, and vitamin B(12).
  
  
  METHODS
  We present a case report of the index case, with clinical and laboratory details. For the investigative analysis, 21 patients who were 18 to 50 years old and had newly diagnosed, untreated Graves' disease and 10 age-and sex-matched euthyroid control subjects were studied. Of the patients with Graves' disease, 11 underwent studies both at diagnosis and after treatment. Fasting blood tests were performed for thyrotropin, free thyroxine, homocys-teine, vitamin B(12), folate, and methylmalonic acid, a marker of vitamin B(12) deficiency.
  
  
  RESULTS
  Vitamin B(12), folate, homocysteine, and methylmalonic acid levels were not significantly different between the thyrotoxic and control or posttreatment groups. In patients with thyrotoxicosis, however, free thyroxine was positively correlated with both homocysteine (r = 0.67; P = 0.03) and methylmalonic acid (r = 0.89; P = 0.003).
  
  
  CONCLUSIONS
  The positive correlation between free thyroxine levels and both homocysteine and methylmalonic acid suggests that thyrotoxicosis may be associated with functional vitamin B(12) deficiency. Such a deficiency may result in clinically important hyperhomocysteine-mia.
authors.affiliation: Department of Internal Medicine, University of New Mexico, School of Medicine, Albuquerque, New Mexico.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Colleran
authors.forename: Devona M
authors.initials: DM
authors.lastname: Ratliff
authors.forename: Mark R
authors.initials: MR
authors.lastname: Burge
mesh_terms: D000293:Adolescent; D000328:Adult; D001777:Blood Coagulation; D005260:Female; D005492:Folic Acid / Q000097:blood; D005494:Folic Acid Deficiency / Q000150:complications*; D006111:Graves Disease / Q000150:complications; D006710:Homocysteine / Q000097:blood* / Q000652:urine; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood; D008764:Methylmalonic Acid / Q000097:blood; D008875:Middle Aged; D012307:Risk Factors; D013923:Thromboembolism / Q000209:etiology*; D013971:Thyrotoxicosis / Q000150:complications*; D013974:Thyroxine / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood; D014804:Vitamin B Deficiency / Q000150:complications*
chemical_list: D006710:Homocysteine; D008764:Methylmalonic Acid; D005492:Folic Acid; D014805:Vitamin B 12; D013974:Thyroxine