title: [Homocysteine after a methionine load in healthy subjects with adequate B-vitamin status].
abstract: BACKGROUND
  Plasma homocysteine (Hcy) determination at 6-8 h after an oral methionine load (OML) allows for identification of some, but not all, individuals at risk to develop cardiovascular disease. It is probable that in some cases the Hcy increases occur later, or it elevates between normal ranges but in a sustained manner. However, the entire Hcy response curve has not been described. We undertook this study to determine Hcy concentrations from baseline to 24- and 48-h after an OML in non-B-vitamin deficient adult subjects with other risk factors for high levels of Hcy such as smoking and overweight.
  
  
  METHODS
  In a cross-over, clinical design, Hcy concentrations were determined at 2-h intervals throughout 12 h and at 24 h and 48 h after an OML (0.1 g/kg). Hcy and vitamin B6 (VB6) concentrations were measured by high-performance liquid chromatography (HPLC). Folic acid (FA) and vitamin B12 (VB12) were measured by radioimmunoassay (RIA). Statistical analysis included delta values and areas under the curve. Student t-test and repeated measurement analyses were conducted to control for confounders.
  
  
  RESULTS
  Twenty-nine subjects with adequate Hcy, FA, VB6 and VB12 status were included. The maximum Hcy concentration occurred 8 h after the load and returned to baseline concentrations after 24 h. All subjects presented Hcy after the load within normal ranges, but smoking and overweight synergistically influenced the response to the challenge, producing a sustained elevation after the dose.
  
  
  CONCLUSIONS
  Hcy concentrations after an OML remained above baseline for at least 24 h. Smoking and overweight affected the response to the methionine challenge.
authors.affiliation: Unidad de Investigación Médica en Nutrición, Hospital de Pediatría, Centro Médico Nacional (CMN) Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), México, D. F., Mexico. marsau2@prodigy.net.mx
authors.forename: Mardia
authors.initials: M
authors.lastname: López-Alarcón
authors.forename: Adolfo
authors.initials: A
authors.lastname: Chávez-Negrete
authors.forename: Irene
authors.initials: I
authors.lastname: Montalvo-Velarde
authors.forename: Jorge
authors.initials: J
authors.lastname: Maldonado-Hernández
authors.forename: Víctor Saúl
authors.initials: VS
authors.lastname: Vital-Reyes
mesh_terms: D000328:Adult; D002318:Cardiovascular Diseases / Q000097:blood* / Q000453:epidemiology; D018592:Cross-Over Studies; D004198:Disease Susceptibility; D042241:Early Diagnosis; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008715:Methionine; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D050177:Overweight / Q000453:epidemiology; D011379:Prognosis; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D013997:Time Factors; D014805:Vitamin B 12 / Q000097:blood*; D025101:Vitamin B 6 / Q000097:blood*; D055815:Young Adult
chemical_list: D006710:Homocysteine; D025101:Vitamin B 6; D005492:Folic Acid; D008715:Methionine; D014805:Vitamin B 12